diff --git a/src/BaseQuantities.zig b/src/BaseQuantities.zig
new file mode 100644
index 0000000..0b9f83e
--- /dev/null
+++ b/src/BaseQuantities.zig
@@ -0,0 +1,95 @@
+const std = @import("std");
+
+// Adjust these imports to match your actual file names
+const Dimensions = @import("Dimensions.zig");
+const Scales = @import("Scales.zig");
+const quantity = @import("quantity.zig");
+const Quantity = quantity.Quantity;
+
+/// Helper function to create a clean namespace for each physical dimension.
+/// It exposes the raw dimensions, and easy type-creators for Base or Scaled variants.
+pub fn QtyNamespace(comptime d: anytype) type {
+    return struct {
+        pub const dims = Dimensions.init(d);
+
+        /// Creates a Quantity of this dimension using default scales.
+        /// Example: const V = Quantities.Velocity.Base(f32);
+        pub fn Base(comptime T: type) type {
+            return Quantity(T, dims, Scales.init(.{}));
+        }
+
+        /// Creates a Quantity of this dimension using custom scales.
+        /// Example: const Kmh = Quantities.Velocity.Scaled(f32, Scales.init(.{ .L = .k, .T = .hour }));
+        pub fn Scaled(comptime T: type, comptime s: Scales) type {
+            return Quantity(T, dims, s);
+        }
+    };
+}
+
+// ==========================================
+// Base Quantities
+// ==========================================
+pub const Meter = QtyNamespace(.{ .L = 1 });
+pub const Second = QtyNamespace(.{ .T = 1 });
+pub const Gramm = QtyNamespace(.{ .M = 1 });
+pub const Kelvin = QtyNamespace(.{ .Tr = 1 });
+pub const ElectricCurrent = QtyNamespace(.{ .I = 1 });
+
+// ==========================================
+// Electric
+// ==========================================
+pub const ElectricConductivity = QtyNamespace(.{ .M = -1, .L = -3, .T = 3, .I = 2 });
+pub const ElectricCharge = QtyNamespace(.{ .T = 1, .I = 1 });
+pub const ElectricPotential = QtyNamespace(.{ .T = -3, .L = 2, .M = 1, .I = -1 });
+pub const ElectricResistance = QtyNamespace(.{ .M = 1, .L = 2, .T = -3, .I = -2 });
+pub const ElectricResistivity = QtyNamespace(.{ .M = 1, .L = 3, .T = -3, .I = -2 });
+pub const ElectricCapacitance = QtyNamespace(.{ .T = 4, .L = -2, .M = -1, .I = 2 });
+pub const ElectricImpedance = ElectricResistance;
+pub const MagneticFlux = QtyNamespace(.{ .M = 1, .L = 2, .T = -2, .I = -1 });
+pub const MagneticDensity = QtyNamespace(.{ .M = 1, .T = -2, .I = -1 });
+pub const MagneticStrength = QtyNamespace(.{ .L = -1, .I = 1 }); // Fixed typo from MagneticStrengh
+pub const MagneticMoment = QtyNamespace(.{ .L = 2, .I = 1 });
+
+// ==========================================
+// Movement
+// ==========================================
+pub const Velocity = QtyNamespace(.{ .L = 1, .T = -1 });
+pub const Acceleration = QtyNamespace(.{ .L = 1, .T = -2 });
+pub const Inertia = QtyNamespace(.{ .M = 1, .L = 2 });
+
+// ==========================================
+// Forces / Energy
+// ==========================================
+pub const Force = QtyNamespace(.{ .T = -2, .M = 1, .L = 1 });
+pub const Pressure = QtyNamespace(.{ .T = -2, .L = -1, .M = 1 });
+pub const Energy = QtyNamespace(.{ .T = -2, .L = 2, .M = 1 });
+pub const Power = QtyNamespace(.{ .T = -3, .L = 2, .M = 1 });
+
+// ==========================================
+// Dimension
+// ==========================================
+pub const Area = QtyNamespace(.{ .L = 2 });
+pub const Volume = QtyNamespace(.{ .L = 3 });
+pub const AreaDensity = QtyNamespace(.{ .M = 1, .L = -2 });
+pub const Density = QtyNamespace(.{ .M = 1, .L = -3 });
+
+// ==========================================
+// Thermal
+// ==========================================
+pub const ThermalHeat = Energy;
+pub const ThermalWork = Energy;
+pub const ThermalCapacity = QtyNamespace(.{ .M = 1, .L = 2, .T = -2, .Tr = -1 });
+pub const ThermalCapacityPerMass = QtyNamespace(.{ .L = 2, .T = -2, .Tr = -1 });
+pub const ThermalFluxDensity = QtyNamespace(.{ .M = 1, .T = -3 }); // Fixed typo from ThermalluxDensity
+pub const ThermalConductance = QtyNamespace(.{ .M = 1, .L = 2, .T = -3, .Tr = -1 });
+pub const ThermalConductivity = QtyNamespace(.{ .M = 1, .L = 1, .T = -3, .Tr = -1 });
+pub const ThermalResistance = QtyNamespace(.{ .M = -1, .L = -2, .T = 3, .Tr = 1 });
+pub const ThermalResistivity = QtyNamespace(.{ .M = -1, .L = -1, .T = 3, .Tr = 1 });
+pub const ThermalEntropy = QtyNamespace(.{ .M = 1, .L = 2, .T = -2, .Tr = -1 });
+
+// ==========================================
+// Others
+// ==========================================
+pub const Frequency = QtyNamespace(.{ .T = -1 });
+pub const Viscosity = QtyNamespace(.{ .M = 1, .L = -1, .T = -1 });
+pub const SurfaceTension = QtyNamespace(.{ .M = 1, .T = -2 }); // Corrected from MT-2a
diff --git a/src/Quantity.zig b/src/Quantity.zig
new file mode 100644
index 0000000..815d756
--- /dev/null
+++ b/src/Quantity.zig
@@ -0,0 +1,529 @@
+const std = @import("std");
+const hlp = @import("helper.zig");
+
+const QuantityVec = @import("QuantityVec.zig").QuantityVec;
+const Scales = @import("Scales.zig");
+const UnitScale = Scales.UnitScale;
+const Dimensions = @import("Dimensions.zig");
+const Dimension = Dimensions.Dimension;
+
+pub fn Quantity(T: type, d: Dimensions, s: Scales) type {
+    return struct {
+        value: T,
+
+        const Self = @This();
+        pub const Vec3: type = QuantityVec(3, Self);
+        pub const ValueType: type = T;
+
+        pub const dims: Dimensions = d;
+        pub const scales = s;
+
+        pub fn add(self: Self, rhs: anytype) Quantity(
+            T,
+            dims,
+            scales.min(@TypeOf(rhs).scales),
+        ) {
+            if (comptime !dims.eql(@TypeOf(rhs).dims))
+                @compileError("Dimension mismatch in add: " ++ dims.str() ++ " vs " ++ @TypeOf(rhs).dims.str());
+
+            const TargetType = Quantity(T, dims, scales.min(@TypeOf(rhs).scales));
+            const lhs_converted = self.to(TargetType);
+            const rhs_converted = rhs.to(TargetType);
+
+            return .{ .value = lhs_converted.value + rhs_converted.value };
+        }
+
+        pub fn sub(self: Self, rhs: anytype) Quantity(
+            T,
+            dims,
+            scales.min(@TypeOf(rhs).scales),
+        ) {
+            if (comptime !dims.eql(@TypeOf(rhs).dims))
+                @compileError("Dimension mismatch in sub: " ++ dims.str() ++ " vs " ++ @TypeOf(rhs).dims.str());
+
+            const TargetType = Quantity(T, dims, scales.min(@TypeOf(rhs).scales));
+            const lhs_converted = self.to(TargetType);
+            const rhs_converted = rhs.to(TargetType);
+
+            return .{ .value = lhs_converted.value - rhs_converted.value };
+        }
+
+        pub fn mulBy(self: Self, rhs: anytype) Quantity(
+            T,
+            dims.add(@TypeOf(rhs).dims),
+            scales.min(@TypeOf(rhs).scales),
+        ) {
+            const self_ = self.to(Quantity(T, dims, scales.min(@TypeOf(rhs).scales)));
+            const rhs_ = rhs.to(Quantity(T, @TypeOf(rhs).dims, scales.min(@TypeOf(rhs).scales)));
+            return .{ .value = self_.value * rhs_.value };
+        }
+
+        pub fn divBy(self: Self, rhs: anytype) Quantity(T, dims.sub(@TypeOf(rhs).dims), scales.min(@TypeOf(rhs).scales)) {
+            const self_ = self.to(Quantity(T, dims, scales.min(@TypeOf(rhs).scales)));
+            const rhs_ = rhs.to(Quantity(T, @TypeOf(rhs).dims, scales.min(@TypeOf(rhs).scales)));
+
+            if (comptime @typeInfo(T) == .int) {
+                return .{ .value = @divTrunc(self_.value, rhs_.value) };
+            } else {
+                return .{ .value = self_.value / rhs_.value };
+            }
+        }
+
+        pub fn scale(self: Self, sc: T) Self {
+            return .{ .value = self.value * sc };
+        }
+
+        pub fn to(self: Self, comptime Dest: type) Dest {
+            if (comptime !dims.eql(Dest.dims))
+                @compileError("Dimension mismatch in to: " ++ dims.str() ++ " vs " ++ Dest.dims.str());
+            if (comptime @TypeOf(self) == Dest)
+                return self;
+
+            const DestT = Dest.ValueType;
+            const ratio = comptime (scales.getFactor(dims) / Dest.scales.getFactor(Dest.dims));
+
+            // Fast-path: Native pure-integer exact conversions
+            if (comptime @typeInfo(T) == .int and @typeInfo(DestT) == .int) {
+                if (ratio >= 1.0 and @round(ratio) == ratio) {
+                    const mult: DestT = @intFromFloat(ratio);
+                    return .{ .value = @as(DestT, @intCast(self.value)) * mult };
+                } else if (ratio < 1.0 and @round(1.0 / ratio) == 1.0 / ratio) {
+                    const div: DestT = @intFromFloat(1.0 / ratio);
+                    const val = @as(DestT, @intCast(self.value));
+                    const half = div / 2;
+                    // Native round-to-nearest
+                    const rounded = if (val >= 0) @divTrunc(val + half, div) else @divTrunc(val - half, div);
+                    return .{ .value = rounded };
+                }
+            }
+
+            // Fallback preserving native Float types (e.g., f128 shouldn't downcast to f64)
+            if (comptime @typeInfo(DestT) == .float) {
+                const val_f = switch (@typeInfo(T)) {
+                    .int => @as(DestT, @floatFromInt(self.value)),
+                    .float => @as(DestT, @floatCast(self.value)),
+                    else => unreachable,
+                };
+                return .{ .value = val_f * @as(DestT, @floatCast(ratio)) };
+            } else {
+                const val_f = switch (@typeInfo(T)) {
+                    .int => @as(f64, @floatFromInt(self.value)),
+                    .float => @as(f64, @floatCast(self.value)),
+                    else => unreachable,
+                };
+                return .{ .value = @intFromFloat(@round(val_f * ratio)) };
+            }
+        }
+        pub fn Vec(self: Self, comptime len: usize) QuantityVec(len, Self) {
+            return QuantityVec(len, Self).initDefault(self.value);
+        }
+
+        pub fn vec3(self: Self) Vec3 {
+            return Vec3.initDefault(self.value);
+        }
+
+        pub fn format(
+            self: Self,
+            writer: *std.Io.Writer,
+        ) !void {
+            try writer.print("{d}", .{self.value});
+            var iter = std.EnumSet(Dimension).initFull().iterator();
+            var first = true;
+            while (iter.next()) |bu| {
+                const v = dims.get(bu);
+                if (v == 0) continue;
+                if (!first)
+                    try writer.writeAll(".");
+
+                first = false;
+
+                const uscale = scales.get(bu);
+                if (bu == .T and (uscale == .min or uscale == .hour or uscale == .year))
+                    try writer.print("{s}", .{uscale.str()})
+                else
+                    try writer.print("{s}{s}", .{ uscale.str(), bu.unit() });
+
+                if (v != 1)
+                    try hlp.printSuperscript(writer, v);
+            }
+        }
+    };
+}
+
+test "Generate quantity" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = -3 }));
+    const Second = Quantity(f32, Dimensions.init(.{ .T = 1 }), Scales.init(.{ .T = .n }));
+
+    const distance = Meter{ .value = 10 };
+    const time = Second{ .value = 2 };
+
+    try std.testing.expectEqual(10, distance.value);
+    try std.testing.expectEqual(2, time.value);
+}
+
+test "Add" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+
+    const distance = Meter{ .value = 10 };
+    const distance2 = Meter{ .value = 20 };
+
+    const added = distance.add(distance2);
+    try std.testing.expectEqual(30, added.value);
+    try std.testing.expectEqual(1, @TypeOf(added).dims.get(.L));
+    std.debug.print("KiloMeter {f} + {f} = {f} OK\n", .{ distance, distance2, added });
+
+    const KiloMeter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const distance3 = KiloMeter{ .value = 2 };
+    const added2 = distance.add(distance3);
+    try std.testing.expectEqual(2010, added2.value);
+    try std.testing.expectEqual(1, @TypeOf(added2).dims.get(.L));
+    std.debug.print("KiloMeter {f} + {f} = {f} OK\n", .{ distance, distance3, added2 });
+
+    const added3 = distance3.add(distance).to(KiloMeter);
+    try std.testing.expectEqual(2, added3.value);
+    try std.testing.expectEqual(1, @TypeOf(added3).dims.get(.L));
+    std.debug.print("KiloMeter {f} + {f} = {f} OK\n", .{ distance3, distance, added3 });
+
+    const KiloMeter_f = Quantity(f64, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const distance4 = KiloMeter_f{ .value = 2 };
+    const added4 = distance4.add(distance).to(KiloMeter_f);
+    try std.testing.expectApproxEqAbs(2.01, added4.value, 0.000001);
+    try std.testing.expectEqual(1, @TypeOf(added4).dims.get(.L));
+    std.debug.print("KiloMeter_f {f} + {f} = {f} OK\n", .{ distance4, distance, added4 });
+}
+
+test "Sub" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const KiloMeter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const KiloMeter_f = Quantity(f64, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+
+    const a = Meter{ .value = 500 };
+    const b = Meter{ .value = 200 };
+    const diff = a.sub(b);
+    try std.testing.expectEqual(300, diff.value);
+    std.debug.print("Sub: {f} - {f} = {f} OK\n", .{ a, b, diff });
+
+    const km = KiloMeter{ .value = 1 };
+    const diff2 = a.sub(km);
+    std.debug.print("Sub cross-scale: {f} - {f} = {f}\n", .{ a, km, diff2 });
+
+    const km_f = KiloMeter_f{ .value = 2.5 };
+    const m_f = Meter{ .value = 500 };
+    const diff3 = km_f.sub(m_f);
+    try std.testing.expectApproxEqAbs(2000, diff3.value, 1e-4);
+    std.debug.print("Sub float cross-scale: {f} - {f} = {f} OK\n", .{ km_f, m_f, diff3 });
+}
+
+test "MulBy" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Second = Quantity(f32, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+    const d = Meter{ .value = 3.0 };
+    const t = Second{ .value = 4.0 };
+
+    const area_time = d.mulBy(t);
+    try std.testing.expectEqual(12, area_time.value);
+    try std.testing.expectEqual(1, @TypeOf(area_time).dims.get(.L));
+    try std.testing.expectEqual(1, @TypeOf(area_time).dims.get(.T));
+    std.debug.print("MulBy: {f} * {f} = {f} OK\n", .{ d, t, area_time });
+
+    const d2 = Meter{ .value = 5.0 };
+    const area = d.mulBy(d2);
+    try std.testing.expectEqual(15, area.value);
+    try std.testing.expectEqual(2, @TypeOf(area).dims.get(.L));
+    try std.testing.expectEqual(0, @TypeOf(area).dims.get(.T));
+    std.debug.print("MulBy: {f} * {f} = {f} OK\n", .{ d, d2, area });
+}
+
+test "MulBy with scale" {
+    const KiloMeter = Quantity(f32, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const KiloGram = Quantity(f32, Dimensions.init(.{ .M = 1 }), Scales.init(.{ .M = .k }));
+
+    const dist = KiloMeter{ .value = 2.0 };
+    const mass = KiloGram{ .value = 3.0 };
+    const prod = dist.mulBy(mass);
+    try std.testing.expectEqual(1, @TypeOf(prod).dims.get(.L));
+    try std.testing.expectEqual(1, @TypeOf(prod).dims.get(.M));
+    std.debug.print("MulBy scaled: {f} * {f} = {f} OK\n", .{ dist, mass, prod });
+}
+
+test "MulBy with type change" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const Second = Quantity(f64, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+    const KmSec = Quantity(i64, Dimensions.init(.{ .L = 1, .T = 1 }), Scales.init(.{ .L = .k }));
+    const KmSec_f = Quantity(f32, Dimensions.init(.{ .L = 1, .T = 1 }), Scales.init(.{ .L = .k }));
+
+    const d = Meter{ .value = 3.0 };
+    const t = Second{ .value = 4.0 };
+
+    const area_time = d.mulBy(t).to(KmSec);
+    const area_time_f = d.mulBy(t).to(KmSec_f);
+    try std.testing.expectEqual(12, area_time.value);
+    try std.testing.expectApproxEqAbs(12, area_time_f.value, 0.0001);
+    try std.testing.expectEqual(1, @TypeOf(area_time).dims.get(.L));
+    try std.testing.expectEqual(1, @TypeOf(area_time).dims.get(.T));
+    std.debug.print("MulBy: {f} * {f} = {f} OK\n", .{ d, t, area_time });
+}
+
+test "MulBy small" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .n }));
+    const Second = Quantity(f32, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+    const d = Meter{ .value = 3.0 };
+    const t = Second{ .value = 4.0 };
+
+    const area_time = d.mulBy(t);
+    try std.testing.expectEqual(12, area_time.value);
+    try std.testing.expectEqual(1, @TypeOf(area_time).dims.get(.L));
+    try std.testing.expectEqual(1, @TypeOf(area_time).dims.get(.T));
+    std.debug.print("MulBy: {f} * {f} = {f} OK\n", .{ d, t, area_time });
+}
+
+test "Scale" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Second = Quantity(f32, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+    const d = Meter{ .value = 7 };
+    const scaled = d.scale(3);
+    try std.testing.expectEqual(21, scaled.value);
+    try std.testing.expectEqual(1, @TypeOf(scaled).dims.get(.L));
+    std.debug.print("Scale int: {f} * 3 = {f} OK\n", .{ d, scaled });
+
+    const t = Second{ .value = 1.5 };
+    const scaled_f = t.scale(4.0);
+    try std.testing.expectApproxEqAbs(@as(f32, 6.0), scaled_f.value, 1e-4);
+    std.debug.print("Scale float: {f} * 4 = {f} OK\n", .{ t, scaled_f });
+}
+
+test "Chained: velocity and acceleration" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Second = Quantity(f32, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+    const dist = Meter{ .value = 100.0 };
+    const t1 = Second{ .value = 5.0 };
+    const velocity = dist.divBy(t1);
+    try std.testing.expectEqual(20, velocity.value);
+    try std.testing.expectEqual(1, @TypeOf(velocity).dims.get(.L));
+    try std.testing.expectEqual(-1, @TypeOf(velocity).dims.get(.T));
+
+    const t2 = Second{ .value = 4.0 };
+    const accel = velocity.divBy(t2);
+    try std.testing.expectEqual(5, accel.value);
+    try std.testing.expectEqual(1, @TypeOf(accel).dims.get(.L));
+    try std.testing.expectEqual(-2, @TypeOf(accel).dims.get(.T));
+
+    std.debug.print("Velocity: {f}, Acceleration: {f} OK\n", .{ velocity, accel });
+}
+
+test "DivBy integer exact" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Second = Quantity(f32, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+    const dist = Meter{ .value = 120 };
+    const time = Second{ .value = 4 };
+    const vel = dist.divBy(time);
+
+    try std.testing.expectEqual(30, vel.value);
+    try std.testing.expectEqual(1, @TypeOf(vel).dims.get(.L));
+    try std.testing.expectEqual(-1, @TypeOf(vel).dims.get(.T));
+    std.debug.print("DivBy int: {f} / {f} = {f} OK\n", .{ dist, time, vel });
+}
+
+test "Conversion chain: km -> m -> cm" {
+    const KiloMeter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const CentiMeter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .c }));
+
+    const km = KiloMeter{ .value = 15 };
+    const m = km.to(Meter);
+    const cm = m.to(CentiMeter);
+
+    try std.testing.expectEqual(15_000, m.value);
+    try std.testing.expectEqual(1_500_000, cm.value);
+    std.debug.print("Chain: {f} -> {f} -> {f} OK\n", .{ km, m, cm });
+}
+
+test "Conversion: hours -> minutes -> seconds" {
+    const Hour = Quantity(i128, Dimensions.init(.{ .T = 1 }), Scales.init(.{ .T = .hour }));
+    const Minute = Quantity(i128, Dimensions.init(.{ .T = 1 }), Scales.init(.{ .T = .min }));
+    const Second = Quantity(i128, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+    const h = Hour{ .value = 1.0 };
+    const min = h.to(Minute);
+    const sec = min.to(Second);
+
+    try std.testing.expectEqual(60, min.value);
+    try std.testing.expectEqual(3600, sec.value);
+    std.debug.print("Time chain: {f} -> {f} -> {f} OK\n", .{ h, min, sec });
+}
+
+test "Negative values" {
+    const Meter = Quantity(i128, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+
+    const a = Meter{ .value = 5 };
+    const b = Meter{ .value = 20 };
+    const diff = a.sub(b);
+    try std.testing.expectEqual(-15, diff.value);
+    std.debug.print("Negative sub: {f} - {f} = {f} OK\n", .{ a, b, diff });
+}
+
+test "Format Quantity" {
+    const MeterPerSecondSq = Quantity(
+        f32,
+        Dimensions.init(.{ .L = 1, .T = -2 }),
+        Scales.init(.{ .T = .n }),
+    );
+    const KgMeterPerSecond = Quantity(
+        f32,
+        Dimensions.init(.{ .M = 1, .L = 1, .T = -1 }),
+        Scales.init(.{ .M = .k }),
+    );
+
+    const accel = MeterPerSecondSq{ .value = 9.81 };
+    const momentum = KgMeterPerSecond{ .value = 42.0 };
+
+    std.debug.print("Acceleration: {f}\n", .{accel});
+    std.debug.print("Momentum: {f}\n", .{momentum});
+}
+
+test "Benchmark" {
+    const Io = std.Io;
+    const ITERS: usize = 100_000;
+    const SAMPLES: usize = 10; // Number of samples for stats
+
+    var gsink: f64 = 0;
+    const io = std.testing.io;
+
+    // Standard Zig 0.16 timestamp retrieval
+    const getTime = struct {
+        fn f(i: Io) Io.Timestamp {
+            return Io.Clock.awake.now(i);
+        }
+    }.f;
+
+    const fold = struct {
+        fn f(comptime TT: type, s: *f64, v: TT) void {
+            s.* += if (comptime @typeInfo(TT) == .float)
+                @as(f64, @floatCast(v))
+            else
+                @as(f64, @floatFromInt(v));
+        }
+    }.f;
+
+    const getVal = struct {
+        fn f(comptime TT: type, i: usize, comptime mask: u7) TT {
+            const v: u8 = @as(u8, @truncate(i & @as(usize, mask))) + 1;
+            return if (comptime @typeInfo(TT) == .float) @floatFromInt(v) else @intCast(v);
+        }
+    }.f;
+
+    const Stats = struct {
+        median: f64,
+        delta: f64,
+        ops_per_sec: f64,
+    };
+
+    const computeStats = struct {
+        fn f(samples: []f64, iters: usize) Stats {
+            std.mem.sort(f64, samples, {}, std.sort.asc(f64));
+            const mid = samples.len / 2;
+            const median_ns = if (samples.len % 2 == 0) (samples[mid - 1] + samples[mid]) / 2.0 else samples[mid];
+
+            const low = samples[0];
+            const high = samples[samples.len - 1];
+            const delta_ns = (high - low) / 2.0;
+
+            const ns_per_op = median_ns / @as(f64, @floatFromInt(iters));
+            return .{
+                .median = ns_per_op,
+                .delta = (delta_ns / @as(f64, @floatFromInt(iters))),
+                .ops_per_sec = 1_000_000_000.0 / ns_per_op,
+            };
+        }
+    }.f;
+
+    std.debug.print(
+        \\
+        \\ Quantity<T> benchmark — {d} iterations, {d} samples/cell
+        \\
+        \\┌───────────────────┬──────┬─────────────────────┬─────────────────────┐
+        \\│ Operation         │ Type │ ns / op (± delta)   │ Throughput (ops/s)  │
+        \\├───────────────────┼──────┼─────────────────────┼─────────────────────┤
+        \\
+    , .{ ITERS, SAMPLES });
+
+    const Types = .{ i16, i32, i64, i128, i256, f32, f64, f128 };
+    const TNames = .{ "i16", "i32", "i64", "i128", "i256", "f32", "f64", "f128" };
+    const Ops = .{ "add", "sub", "mulBy", "divBy", "scale", "to" };
+
+    var results_matrix: [Ops.len][Types.len]f64 = undefined;
+
+    comptime var tidx: usize = 0;
+    inline for (Types, TNames) |T, tname| {
+        const M = Quantity(T, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+        const KM = Quantity(T, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+        const S = Quantity(T, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+
+        inline for (Ops, 0..) |op_name, oidx| {
+            var samples: [SAMPLES]f64 = undefined;
+
+            for (0..SAMPLES) |s_idx| {
+                var sink: T = 0;
+                const t_start = getTime(io);
+
+                for (0..ITERS) |i| {
+                    const r = if (comptime std.mem.eql(u8, op_name, "add"))
+                        (M{ .value = getVal(T, i, 63) }).add(M{ .value = getVal(T, i +% 7, 63) })
+                    else if (comptime std.mem.eql(u8, op_name, "sub"))
+                        (M{ .value = getVal(T, i +% 10, 63) }).sub(M{ .value = getVal(T, i, 63) })
+                    else if (comptime std.mem.eql(u8, op_name, "mulBy"))
+                        (M{ .value = getVal(T, i, 63) }).mulBy(M{ .value = getVal(T, i +% 1, 63) })
+                    else if (comptime std.mem.eql(u8, op_name, "divBy"))
+                        (M{ .value = getVal(T, i +% 10, 63) }).divBy(S{ .value = getVal(T, i, 63) })
+                    else if (comptime std.mem.eql(u8, op_name, "scale"))
+                        (M{ .value = getVal(T, i, 63) }).scale(getVal(T, i +% 2, 63))
+                    else
+                        (KM{ .value = getVal(T, i, 15) }).to(M);
+
+                    if (comptime @typeInfo(T) == .float) sink += r.value else sink ^= r.value;
+                }
+
+                const t_end = getTime(io);
+                samples[s_idx] = @as(f64, @floatFromInt(t_start.durationTo(t_end).toNanoseconds()));
+                fold(T, &gsink, sink);
+            }
+
+            const stats = computeStats(&samples, ITERS);
+            results_matrix[oidx][tidx] = stats.median;
+
+            std.debug.print("│ {s:<17} │ {s:<4} │ {d:>8.2} ns ±{d:<6.2} │ {d:>19.0} │\n", .{ op_name, tname, stats.median, stats.delta, stats.ops_per_sec });
+        }
+
+        if (comptime tidx < Types.len - 1) {
+            std.debug.print("├───────────────────┼──────┼─────────────────────┼─────────────────────┤\n", .{});
+        }
+        tidx += 1;
+    }
+
+    // Median Summary Table
+    std.debug.print("└───────────────────┴──────┴─────────────────────┴─────────────────────┘\n\n", .{});
+    std.debug.print("Median Summary (ns/op):\n", .{});
+
+    std.debug.print("┌──────────────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┬───────┐\n", .{});
+    std.debug.print("│  Operation   │  i16  │  i32  │  i64  │  i128 │  i256 │  f32  │  f64  │  f128 │\n", .{});
+    std.debug.print("├──────────────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┼───────┤\n", .{});
+
+    inline for (Ops, 0..) |op_name, oidx| {
+        std.debug.print("│  {s:<11} │", .{op_name});
+        var i: usize = 0;
+        while (i < Types.len) : (i += 1) {
+            std.debug.print("{d:>6.1} │", .{results_matrix[oidx][i]});
+        }
+        std.debug.print("\n", .{});
+    }
+
+    std.debug.print("└──────────────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┴───────┘\n", .{});
+
+    std.debug.print("\nAnti-optimisation sink: {d:.4}\n", .{gsink});
+    try std.testing.expect(gsink != 0);
+}
diff --git a/src/QuantityVec.zig b/src/QuantityVec.zig
new file mode 100644
index 0000000..b9a544a
--- /dev/null
+++ b/src/QuantityVec.zig
@@ -0,0 +1,307 @@
+const std = @import("std");
+const hlp = @import("helper.zig");
+
+const Quantity = @import("Quantity.zig");
+const Scales = @import("Scales.zig");
+const UnitScale = Scales.UnitScale;
+const Dimensions = @import("Dimensions.zig");
+const Dimension = Dimensions.Dimension;
+
+pub fn QuantityVec(comptime len: usize, comptime Q: type) type {
+    const T = Q.ValueType;
+    const d: Dimensions = Q.dims;
+    const s: Scales = Q.scales;
+
+    return struct {
+        data: [len]T,
+
+        const Self = @This();
+        pub const QuantityType = Q;
+        pub const ValueType = T;
+        pub const dims: Dimensions = d;
+        pub const scales = s;
+
+        pub const zero = initDefault(0);
+        pub const one = initDefault(1);
+
+        pub fn initDefault(v: T) Self {
+            var data: [len]T = undefined;
+            for (&data) |*item| item.* = v;
+            return .{ .data = data };
+        }
+
+        pub fn add(self: Self, rhs: anytype) QuantityVec(len, Quantity(T, d, s.min(@TypeOf(rhs).scales))) {
+            const Tr = @TypeOf(rhs);
+            var res: QuantityVec(len, Quantity(T, d, s.min(Tr.scales))) = undefined;
+            for (self.data, 0..) |v, i| {
+                const q = (Q{ .value = v }).add(Tr.QuantityType{ .value = rhs.data[i] });
+                res.data[i] = q.value;
+            }
+            return res;
+        }
+
+        pub fn sub(self: Self, rhs: anytype) QuantityVec(len, Quantity(T, d, s.min(@TypeOf(rhs).scales))) {
+            const Tr = @TypeOf(rhs);
+            var res: QuantityVec(len, Quantity(T, d, s.min(Tr.scales))) = undefined;
+            for (self.data, 0..) |v, i| {
+                const q = (Q{ .value = v }).sub(Tr.QuantityType{ .value = rhs.data[i] });
+                res.data[i] = q.value;
+            }
+            return res;
+        }
+
+        pub fn divBy(
+            self: Self,
+            rhs: anytype,
+        ) QuantityVec(len, Quantity(T, d.sub(@TypeOf(rhs).dims), s.min(@TypeOf(rhs).scales))) {
+            const Tr = @TypeOf(rhs);
+            var res: QuantityVec(len, Quantity(T, d.sub(Tr.dims), s.min(Tr.scales))) = undefined;
+            for (self.data, 0..) |v, i| {
+                const q = (Q{ .value = v }).divBy(Tr.QuantityType{ .value = rhs.data[i] });
+                res.data[i] = q.value;
+            }
+            return res;
+        }
+
+        pub fn mulBy(
+            self: Self,
+            rhs: anytype,
+        ) QuantityVec(len, Quantity(T, d.add(@TypeOf(rhs).dims), s.min(@TypeOf(rhs).scales))) {
+            const Tr = @TypeOf(rhs);
+            var res: QuantityVec(len, Quantity(T, d.add(Tr.dims), s.min(Tr.scales))) = undefined;
+            for (self.data, 0..) |v, i| {
+                const q = (Q{ .value = v }).mulBy(Tr.QuantityType{ .value = rhs.data[i] });
+                res.data[i] = q.value;
+            }
+            return res;
+        }
+
+        pub fn divByScalar(
+            self: Self,
+            scalar: anytype,
+        ) QuantityVec(len, Quantity(T, d.sub(@TypeOf(scalar).dims), s.min(@TypeOf(scalar).scales))) {
+            var res: QuantityVec(len, Quantity(T, d.sub(@TypeOf(scalar).dims), s.min(@TypeOf(scalar).scales))) = undefined;
+            for (self.data, 0..) |v, i| {
+                const q = Q{ .value = v };
+                res.data[i] = q.divBy(scalar).value;
+            }
+            return res;
+        }
+
+        pub fn mulByScalar(
+            self: Self,
+            scalar: anytype,
+        ) QuantityVec(len, Quantity(T, d.add(@TypeOf(scalar).dims), s.min(@TypeOf(scalar).scales))) {
+            var res: QuantityVec(len, Quantity(T, d.add(@TypeOf(scalar).dims), s.min(@TypeOf(scalar).scales))) = undefined;
+            for (self.data, 0..) |v, i| {
+                const q = Q{ .value = v };
+                res.data[i] = q.mulBy(scalar).value;
+            }
+            return res;
+        }
+
+        pub fn negate(self: Self) Self {
+            var res: Self = undefined;
+            for (self.data, 0..) |v, i| {
+                res.data[i] = -v;
+            }
+            return res;
+        }
+
+        pub fn scale(self: Self, rhs: T) Self {
+            var res: Self = undefined;
+            for (self.data, 0..) |v, i| {
+                res.data[i] = (Q{ .value = v }).scale(rhs).value;
+            }
+            return res;
+        }
+
+        pub fn to(self: Self, comptime DestQ: type) QuantityVec(len, DestQ) {
+            var res: QuantityVec(len, DestQ) = undefined;
+            for (self.data, 0..) |v, i| {
+                res.data[i] = (Q{ .value = v }).to(DestQ).value;
+            }
+            return res;
+        }
+
+        pub fn lengthSqr(self: Self) T {
+            var sum: T = 0;
+            for (self.data) |v| {
+                sum += v * v;
+            }
+            return sum;
+        }
+
+        pub fn length(self: Self) T {
+            const len_sq = self.lengthSqr();
+
+            if (comptime @typeInfo(T) == .int) {
+                // Construct the unsigned equivalent of T at comptime (e.g., i32 -> u32)
+                const UnsignedT = @Int(.unsigned, @typeInfo(T).int.bits);
+
+                // len_sq is always positive, so @intCast is perfectly safe
+                const u_len_sq = @as(UnsignedT, @intCast(len_sq));
+                return @as(T, @intCast(std.math.sqrt(u_len_sq)));
+            } else {
+                return @sqrt(len_sq);
+            }
+        }
+
+        pub fn format(self: Self, writer: *std.Io.Writer) !void {
+            try writer.writeAll("(");
+            for (self.data, 0..) |v, i| {
+                if (i > 0) try writer.writeAll(", ");
+                try writer.print("{d:.2}", .{v});
+            }
+            try writer.writeAll(")");
+            var iter = std.EnumSet(Dimension).initFull().iterator();
+            var first = true;
+            while (iter.next()) |bu| {
+                const v = dims.get(bu);
+                if (v == 0) continue;
+                if (!first) try writer.writeAll(".");
+                first = false;
+                try writer.print("{s}{s}", .{ scales.get(bu).str(), bu.unit() });
+                if (v != 1) try hlp.printSuperscript(writer, v);
+            }
+        }
+    };
+}
+
+test "Format VectorX" {
+    const MeterPerSecondSq = Quantity(
+        f32,
+        Dimensions.init(.{ .L = 1, .T = -2 }),
+        Scales.init(.{ .T = .n }),
+    );
+    const KgMeterPerSecond = Quantity(
+        f32,
+        Dimensions.init(.{ .M = 1, .L = 1, .T = -1 }),
+        Scales.init(.{ .M = .k }),
+    );
+
+    const accel = MeterPerSecondSq.Vec3.initDefault(9.81);
+    const momentum = KgMeterPerSecond.Vec3{ .data = .{ 43, 0, 11 } };
+
+    std.debug.print("Acceleration: {f}\n", .{accel});
+    std.debug.print("Momentum: {f}\n", .{momentum});
+}
+
+test "VecX Init and Basic Arithmetic" {
+    const Meter = Quantity(i32, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Vec3M = Meter.Vec3;
+
+    // Test zero, one, initDefault
+    const v_zero = Vec3M.zero;
+    try std.testing.expectEqual(0, v_zero.data[0]);
+    try std.testing.expectEqual(0, v_zero.data[1]);
+    try std.testing.expectEqual(0, v_zero.data[2]);
+
+    const v_one = Vec3M.one;
+    try std.testing.expectEqual(1, v_one.data[0]);
+    try std.testing.expectEqual(1, v_one.data[1]);
+    try std.testing.expectEqual(1, v_one.data[2]);
+
+    const v_def = Vec3M.initDefault(5);
+    try std.testing.expectEqual(5, v_def.data[0]);
+    try std.testing.expectEqual(5, v_def.data[1]);
+    try std.testing.expectEqual(5, v_def.data[2]);
+
+    // Test add and sub
+    const v1 = Vec3M{ .data = .{ 10, 20, 30 } };
+    const v2 = Vec3M{ .data = .{ 2, 4, 6 } };
+
+    const added = v1.add(v2);
+    try std.testing.expectEqual(12, added.data[0]);
+    try std.testing.expectEqual(24, added.data[1]);
+    try std.testing.expectEqual(36, added.data[2]);
+
+    const subbed = v1.sub(v2);
+    try std.testing.expectEqual(8, subbed.data[0]);
+    try std.testing.expectEqual(16, subbed.data[1]);
+    try std.testing.expectEqual(24, subbed.data[2]);
+
+    // Test negate
+    const neg = v1.negate();
+    try std.testing.expectEqual(-10, neg.data[0]);
+    try std.testing.expectEqual(-20, neg.data[1]);
+    try std.testing.expectEqual(-30, neg.data[2]);
+}
+
+test "VecX Kinematics (Scalar Mul/Div)" {
+    const Meter = Quantity(i32, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Second = Quantity(i32, Dimensions.init(.{ .T = 1 }), Scales.init(.{}));
+    const Vec3M = Meter.Vec3;
+
+    const pos = Vec3M{ .data = .{ 100, 200, 300 } };
+    const time = Second{ .value = 10 };
+
+    // Vector divided by scalar Quantity (Velocity = Position / Time)
+    const vel = pos.divByScalar(time);
+    try std.testing.expectEqual(10, vel.data[0]);
+    try std.testing.expectEqual(20, vel.data[1]);
+    try std.testing.expectEqual(30, vel.data[2]);
+    try std.testing.expectEqual(1, @TypeOf(vel).dims.get(.L));
+    try std.testing.expectEqual(-1, @TypeOf(vel).dims.get(.T));
+
+    // Vector multiplied by scalar Quantity (Position = Velocity * Time)
+    const new_pos = vel.mulByScalar(time);
+    try std.testing.expectEqual(100, new_pos.data[0]);
+    try std.testing.expectEqual(200, new_pos.data[1]);
+    try std.testing.expectEqual(300, new_pos.data[2]);
+    try std.testing.expectEqual(1, @TypeOf(new_pos).dims.get(.L));
+    try std.testing.expectEqual(0, @TypeOf(new_pos).dims.get(.T));
+}
+
+test "VecX Element-wise Math and Scaling" {
+    const Meter = Quantity(i32, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const Vec3M = Meter.Vec3;
+
+    const v1 = Vec3M{ .data = .{ 10, 20, 30 } };
+    const v2 = Vec3M{ .data = .{ 2, 5, 10 } };
+
+    // Element-wise division
+    const div = v1.divBy(v2);
+    try std.testing.expectEqual(5, div.data[0]);
+    try std.testing.expectEqual(4, div.data[1]);
+    try std.testing.expectEqual(3, div.data[2]);
+    try std.testing.expectEqual(0, @TypeOf(div).dims.get(.L)); // M / M = Dimensionless
+
+    // Scale by primitive
+    const scaled = v1.scale(2);
+    try std.testing.expectEqual(20, scaled.data[0]);
+    try std.testing.expectEqual(40, scaled.data[1]);
+    try std.testing.expectEqual(60, scaled.data[2]);
+}
+
+test "VecX Conversions" {
+    const KiloMeter = Quantity(i32, Dimensions.init(.{ .L = 1 }), Scales.init(.{ .L = .k }));
+    const Meter = Quantity(i32, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+
+    const v_km = KiloMeter.Vec3{ .data = .{ 1, 2, 3 } };
+    const v_m = v_km.to(Meter);
+
+    try std.testing.expectEqual(1000, v_m.data[0]);
+    try std.testing.expectEqual(2000, v_m.data[1]);
+    try std.testing.expectEqual(3000, v_m.data[2]);
+
+    // Type checking the result
+    try std.testing.expectEqual(1, @TypeOf(v_m).dims.get(.L));
+    try std.testing.expectEqual(UnitScale.none, @TypeOf(v_m).scales.get(.L));
+}
+
+test "VecX Length" {
+    const MeterInt = Quantity(i32, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+    const MeterFloat = Quantity(f32, Dimensions.init(.{ .L = 1 }), Scales.init(.{}));
+
+    // Integer length (using your custom isqrt)
+    // 3-4-5 triangle on XY plane
+    const v_int = MeterInt.Vec3{ .data = .{ 3, 4, 0 } };
+    try std.testing.expectEqual(25, v_int.lengthSqr());
+    try std.testing.expectEqual(5, v_int.length());
+
+    // Float length
+    const v_float = MeterFloat.Vec3{ .data = .{ 3.0, 4.0, 0.0 } };
+    try std.testing.expectApproxEqAbs(@as(f32, 25.0), v_float.lengthSqr(), 1e-4);
+    try std.testing.expectApproxEqAbs(@as(f32, 5.0), v_float.length(), 1e-4);
+}