Unit Converter (Engineering Units)

How to use the unit converter

Pick the quantity (length, pressure, power and so on), type the value and choose its unit from the list beside it. The tool shows the value in every unit of that quantity in one table. The result updates as you type. The button on each row copies that value to the clipboard. Your last quantity and unit are remembered in your browser.

Which quantities are covered?

• Basic: length, area, volume, mass, time, temperature, angle
• Mechanics: force, pressure, stress, torque, speed, acceleration, rotational speed, density, line load, second moment of area
• Energy and power: watts, kilowatts, horsepower, BTU/h, kcal/h, tons of refrigeration, joules, kilowatt hours, calories
• Fluids and heat: volume and mass flow rate, viscosity, specific heat
• Electrical: voltage, current, resistance, apparent and reactive power, capacitance, inductance

Common conversions

• 1 bar = 100 kPa = 14.504 psi = 1.0197 kgf/cm²
• 1 inch = 25.4 mm, 1 foot = 0.3048 m
• 1 kW = 1.341 hp (mechanical) = 1.360 PS (metric)
• 12 000 BTU/h = 3.517 kW = 1 ton of refrigeration
• 1 kWh = 3.6 MJ = 859.8 kcal
• 1 kgf = 9.80665 N, 1 N·m = 0.7376 lbf·ft

Take care with temperature

Temperature converts with an offset, not just a factor: °F = °C × 9/5 + 32. A reading of 10 °C is 50 °F. But a difference of 10 °C between two temperatures is a difference of 18 °F. When a heat calculation needs a difference, choose the "Temperature difference" quantity.

Two kinds of horsepower

Mechanical horsepower (hp) is 745.7 W and metric horsepower (PS) is 735.5 W. Check which one a catalogue uses: they differ by 1.4 percent.

Where do the factors come from?

The factors are defined values: the inch is exactly 25.4 mm, the pound exactly 0.45359237 kg and standard gravity exactly 9.80665 m/s². Calories and BTU use the International Table (IT) definition: 1 cal = 4.1868 J and 1 BTU = 1055.056 J. The gallon is the US liquid gallon (3.785 L). mmHg and mH₂O are conventional values.