Unit Converter: kW to hp, Nm, bar and psi
Convert the physical quantities common in mechanical engineering between metric and US customary units: power, rotational speed, torque, pressure, force, energy, length, mass, speed and temperature. Each quantity has its own card - enter a value, pick the source unit, and every target unit appears instantly, live with every input.
Calculation
Power
Rotational speed
Torque
Pressure
Force
Energy
Length
Mass
Speed
Temperature
All cards convert factor-based through an SI base unit; temperature uses an affine conversion with a zero-point offset and applies to absolute values only, not to temperature differences. The display rounds to six significant figures.
Calculation in your browser, inputs go to our server only when you export or save.
Formulas and fundamentals
Converting kW to PS and PS to kW (power)
Factor-based quantities are converted through a common SI base unit: the input value is scaled into the base by the source unit's factor and then divided by the target unit's factor. For power the base is the watt, with:
Converting pressure (bar, psi, Pa, MPa)
For pressure the base is the pascal, with:
Converting force, length and mass
Force, length and mass follow the same scheme. Force in newtons:
Converting Nm (torque)
Torque in newton metres:
Length in metres:
Mass in kilograms:
The constant 9.80665 m/s² is the standard gravitational acceleration that defines all kilopond units (kp, kp·m).
Temperature (affine conversion)
Temperature is the only quantity with an affine conversion because the scales have different zero points. Celsius maps to the kelvin base via:
Fahrenheit via:
The reverse conversion inverts the relation. Hence 0 °C = 273.15 K = 32 °F, and a temperature difference of 1 K equals 1 °C but 1.8 °F.
Worked example
A motor delivers 100 kW. In the Power card you enter 100 and select kW as the source unit. The converter immediately shows 135.96 PS and 134.10 hp - the difference between metric PS and mechanical horsepower is about 1.4 percent and is often overlooked in practice.
A hydraulic pressure of 1 bar equals 14.50 psi, 100,000 Pa and 0.1 MPa. A tightening torque of 100 Nm equals 73.76 lb·ft and 10.20 kp·m. A length of 1000 mm is exactly 39.37 in and 3.281 ft.
For temperature the converter shows 293.15 K and 68 °F for 20 °C. Important: these cards convert absolute values, not temperature differences. A difference of 10 K does equal 10 °C, but 10 °C is not 50 °F - here the factor 1.8 applies (i.e. 18 °F).
Frequently asked questions
How do I convert kW to PS?
To convert kilowatts to PS, multiply by 1000 and divide by 735.49875 (factor ≈ 1.3596). 100 kW gives 135.96 PS. To convert PS to kW, do the reverse: multiply by 735.49875 and divide by 1000.
What is the difference between PS and hp?
PS is metric horsepower (1 PS = 735.49875 W = 75 kp·m/s), hp is US/UK mechanical horsepower (1 hp = 745.699872 W). One hp is about 1.4 percent stronger than one PS. Vehicle and motor ratings from English-speaking markets almost always mean hp.
How do I convert Nm, for example to lb·ft or kp·m?
To convert Nm to lb·ft, divide by 1.355818; to convert Nm to kp·m, divide by 9.80665. 100 Nm equals 73.76 lb·ft and 10.20 kp·m. The torque card gives both values at once from a single input.
What does kp mean and why does 9.80665 appear?
kp stands for kilopond, the old technical unit of force: 1 kp is the weight force of 1 kg under the standard gravitational acceleration g = 9.80665 m/s². Hence 1 kp = 9.80665 N and 1 kp·m = 9.80665 Nm. Modern calculations use newtons consistently, but kp still appears on older drawings and datasheets.
Does the tool convert temperature differences or absolute values?
Absolute values. The temperature card uses the full scale offset (0 °C = 273.15 K = 32 °F). Temperature differences follow different rules: 1 K = 1 °C = 1.8 °F, with no offset. Use the card only for individual temperature readings, not for spans.
Why is 1 bar not exactly 1 kg/cm²?
1 bar = 100,000 Pa is a decimal unit, whereas the technical atmosphere at (kp/cm²) depends on gravity: 1 at = 98,066.5 Pa. The difference is about 2 percent. This converter works with bar, Pa, kPa, MPa and psi; for rough estimates 1 bar ≈ 1 kg/cm² is nonetheless often used.
How accurate are the conversion factors?
The factors match the defined or generally accepted values (e.g. 1 in = 25.4 mm exactly, 1 lb = 0.45359237 kg exactly, 1 psi = 6894.757 Pa). The display rounds to six significant figures. For billing or certification purposes the applicable standard values govern.
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