Units
Length
| From | Equals |
|---|---|
| 1 inch | 25.4 mm |
| 1 foot | 0.3048 m |
| 1 yard | 0.9144 m |
| 1 mile | 1.609 km |
| 1 mm | 0.03937 in |
| 1 m | 3.281 ft |
Area
| From | Equals |
|---|---|
| 1 in² | 645.16 mm² |
| 1 ft² | 0.0929 m² |
| 1 m² | 10.764 ft² |
| 1 acre | 0.4047 ha |
| 1 hectare | 2.471 acres |
Volume
| From | Equals |
|---|---|
| 1 litre | 1000 cm³ |
| 1 US gallon | 3.785 L |
| 1 UK gallon | 4.546 L |
| 1 ft³ | 28.317 L |
| 1 m³ | 1000 L = 35.31 ft³ |
Mass
| From | Equals |
|---|---|
| 1 lb | 0.4536 kg |
| 1 oz | 28.35 g |
| 1 kg | 2.2046 lb |
| 1 short ton (US) | 907.2 kg |
| 1 long ton (UK) | 1016 kg |
Force
| From | Equals |
|---|---|
| 1 kgf | 9.807 N |
| 1 lbf | 4.448 N |
| 1 kN | 224.8 lbf = 102 kgf |
| 1 tonne-force | 9.807 kN |
Pressure
| From | Equals |
|---|---|
| 1 bar | 100 kPa = 14.504 psi |
| 1 psi | 6.895 kPa = 0.0689 bar |
| 1 MPa | 1 N/mm² = 145.0 psi |
| 1 kgf/cm² | 0.981 bar = 14.22 psi |
| 1 atmosphere | 1.013 bar |
Torque
| From | Equals |
|---|---|
| 1 Nm | 0.7376 ft-lb = 8.851 in-lb |
| 1 ft-lb | 1.356 Nm |
| 1 in-lb | 0.1130 Nm |
| 1 kgf·m | 9.807 Nm |
Power & energy
| From | Equals |
|---|---|
| 1 kW | 1.341 hp |
| 1 hp | 0.7457 kW |
| 1 PS (metric hp) | 0.7355 kW |
| 1 kWh | 3.6 MJ |
| 1 BTU | 1.055 kJ |
| 1 kcal | 4.187 kJ |
Flow & speed
| From | Equals |
|---|---|
| 1 m³/h | 16.67 L/min |
| 1 US gal/min | 3.785 L/min |
| 1 cfm | 28.32 L/min |
| 1 m/s | 3.6 km/h = 196.9 ft/min |
| 1 mph | 1.609 km/h |
Temperature and hardness
Temperature
| °C | °F |
|---|---|
| -40 | -40 |
| -20 | -4 |
| -10 | 14 |
| 0 | 32 |
| 10 | 50 |
| 20 | 68 |
| 37 | 99 |
| 50 | 122 |
| 100 | 212 |
| 150 | 302 |
| 200 | 392 |
| 250 | 482 |
| 300 | 572 |
| 400 | 752 |
| 500 | 932 |
| 600 | 1112 |
| 800 | 1472 |
| 1000 | 1832 |
| 1200 | 2192 |
| 1500 | 2732 |
- °F = °C × 1.8 + 32
- °C = (°F − 32) ÷ 1.8
- K = °C + 273.15
Hardness (steel, ASTM E140)
| HRC | HV | HB | Tensile ≈ MPa |
|---|---|---|---|
| 65 | 832 | - | - |
| 60 | 697 | - | - |
| 58 | 653 | - | - |
| 55 | 595 | - | - |
| 52 | 544 | - | - |
| 50 | 513 | 481 | 1660 |
| 48 | 484 | 456 | 1570 |
| 45 | 446 | 421 | 1450 |
| 42 | 412 | 390 | 1350 |
| 40 | 392 | 371 | 1280 |
| 38 | 372 | 353 | 1220 |
| 35 | 345 | 327 | 1130 |
| 32 | 318 | 301 | 1040 |
| 30 | 302 | 286 | 990 |
| 28 | 286 | 271 | 930 |
| 25 | 266 | 253 | 870 |
| 22 | 248 | 237 | 820 |
| 20 | 238 | 226 | 780 |
Hardness conversions are approximate and valid for carbon and alloy steels only. Brinell is not used above about HRC 50. Tensile strength ≈ 3.45 × HB is an estimate, not a test result.
Fractions to decimals and millimetres
| Inch | Decimal | mm |
|---|---|---|
| 1/64" | 0.0156 | 0.397 |
| 1/32" | 0.0312 | 0.794 |
| 3/64" | 0.0469 | 1.191 |
| 1/16" | 0.0625 | 1.587 |
| 5/64" | 0.0781 | 1.984 |
| 3/32" | 0.0938 | 2.381 |
| 7/64" | 0.1094 | 2.778 |
| 1/8" | 0.1250 | 3.175 |
| 9/64" | 0.1406 | 3.572 |
| 5/32" | 0.1562 | 3.969 |
| 11/64" | 0.1719 | 4.366 |
| 3/16" | 0.1875 | 4.762 |
| 13/64" | 0.2031 | 5.159 |
| 7/32" | 0.2188 | 5.556 |
| 15/64" | 0.2344 | 5.953 |
| 1/4" | 0.2500 | 6.350 |
| 17/64" | 0.2656 | 6.747 |
| 9/32" | 0.2812 | 7.144 |
| 19/64" | 0.2969 | 7.541 |
| 5/16" | 0.3125 | 7.938 |
| 21/64" | 0.3281 | 8.334 |
| 11/32" | 0.3438 | 8.731 |
| 23/64" | 0.3594 | 9.128 |
| 3/8" | 0.3750 | 9.525 |
| 25/64" | 0.3906 | 9.922 |
| 13/32" | 0.4062 | 10.319 |
| 27/64" | 0.4219 | 10.716 |
| 7/16" | 0.4375 | 11.112 |
| 29/64" | 0.4531 | 11.509 |
| 15/32" | 0.4688 | 11.906 |
| 31/64" | 0.4844 | 12.303 |
| 1/2" | 0.5000 | 12.700 |
| Inch | Decimal | mm |
|---|---|---|
| 33/64" | 0.5156 | 13.097 |
| 17/32" | 0.5312 | 13.494 |
| 35/64" | 0.5469 | 13.891 |
| 9/16" | 0.5625 | 14.287 |
| 37/64" | 0.5781 | 14.684 |
| 19/32" | 0.5938 | 15.081 |
| 39/64" | 0.6094 | 15.478 |
| 5/8" | 0.6250 | 15.875 |
| 41/64" | 0.6406 | 16.272 |
| 21/32" | 0.6562 | 16.669 |
| 43/64" | 0.6719 | 17.066 |
| 11/16" | 0.6875 | 17.462 |
| 45/64" | 0.7031 | 17.859 |
| 23/32" | 0.7188 | 18.256 |
| 47/64" | 0.7344 | 18.653 |
| 3/4" | 0.7500 | 19.050 |
| 49/64" | 0.7656 | 19.447 |
| 25/32" | 0.7812 | 19.844 |
| 51/64" | 0.7969 | 20.241 |
| 13/16" | 0.8125 | 20.637 |
| 53/64" | 0.8281 | 21.034 |
| 27/32" | 0.8438 | 21.431 |
| 55/64" | 0.8594 | 21.828 |
| 7/8" | 0.8750 | 22.225 |
| 57/64" | 0.8906 | 22.622 |
| 29/32" | 0.9062 | 23.019 |
| 59/64" | 0.9219 | 23.416 |
| 15/16" | 0.9375 | 23.812 |
| 61/64" | 0.9531 | 24.209 |
| 31/32" | 0.9688 | 24.606 |
| 63/64" | 0.9844 | 25.003 |
| 1" | 1.0000 | 25.400 |
Densities and steel weights
Densities
| Material | Density g/cm³ |
|---|---|
| Steel | 7.85 |
| Stainless steel | 7.9 - 8.0 |
| Cast iron | 7.2 |
| Aluminium | 2.70 |
| Copper | 8.96 |
| Brass | 8.4 - 8.7 |
| Lead | 11.3 |
| Titanium | 4.51 |
| Water | 1.00 |
Steel weight formulas
- Round bar: kg/m = 0.006165 × d²
- Square bar: kg/m = 0.00785 × a²
- Flat bar: kg/m = 0.00785 × w × t
- Plate: kg/m² = 7.85 × t
- Tube: kg/m = 0.02466 × t × (D − t)
- All dimensions in mm, steel. Multiply by 1.01 for stainless and 0.344 for aluminium.