Unit Conversion Calculator

Inches to millimetres and kilograms to pounds

Use this free unit converter for drawing dimensions, stock weights, coolant temperature and pressure values. Length, mass, temperature and pressure each have their own compatible unit choices. Kilometres are a length unit; kilograms and pounds are mass units.

Exact length and mass relationships

Millimetres = inches × 25.4. Inches = millimetres / 25.4. One foot is 12 inches, or 0.3048 metres. One international mile is 1.609344 kilometres.

Kilograms = pounds × 0.45359237. Pounds = kilograms / 0.45359237. An avoirdupois ounce is 1/16 of a pound.

Worked conversion examples

• 2 in = 50.8 mm.
• 25.4 mm = 1 in.
• 10 kg ≈ 22.04622622 lb.
• 5 lb = 2.26796185 kg.
• 68°F = 20°C.
• 1 bar = 100 kPa.

Temperature and pressure formulas

°C = (°F − 32) × 5 / 9. °F = °C × 9 / 5 + 32. K = °C + 273.15. Temperatures below absolute zero are rejected. Temperature conversion applies to absolute readings, not temperature differences.

Pressure uses pascals as the common base: 1 bar = 100,000 Pa, 1 MPa = 1,000,000 Pa, and 1 psi ≈ 6,894.757293 Pa. Converting a gauge-pressure number preserves its reference; it does not turn it into absolute pressure.

Values use full precision internally; displayed results are rounded. Very small and large results use scientific notation. Converting units does not increase the accuracy of a measurement.

Conversion reference: NIST conversion factors.

Need weight from stock dimensions?

The material weight calculator estimates round bar, tube, plate and hex-bar weight using material density. For cutting calculations, explore the machinist toolbox.