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Power Converter — KM, kW, HP, W
Power is a physical quantity that describes the rate of doing work or transferring energy. Different regions and industries use different units, which often causes confusion. The most common units are: kilowatt (kW) — the SI unit used across the EU; metric horsepower (KM / PS / CV) — common in Europe; SAE horsepower (HP) — standard in the USA and Canada; and watt (W) — the fundamental SI unit of power. European Union law requires that vehicle engine power be stated in kilowatts (kW) on registration documents and nameplates, although manufacturers usually list KM alongside it. The difference between KM and HP is small but real: 1 metric KM = 0.7355 kW, while 1 SAE HP = 0.7457 kW — a difference of about 1.4%. This power converter instantly converts any value between all four units simultaneously. Enter the number, select the source unit, and the calculator immediately shows results in kW, KM, HP and W.
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How the power converter works
The calculator converts all values via kilowatt as the intermediate unit: 1. Input value -> kW: value x conversion_factor_to_kW - 1 KM = 0.7354988 kW - 1 HP = 0.7456999 kW - 1 W = 0.001 kW 2. From kW -> all other units: - KM = kW / 0.7354988 - HP = kW / 0.7456999 - W = kW x 1000 Results are rounded to 4 decimal places for kW, KM and HP, and 1 decimal place for W. Input of 0 returns all zeros.
Example: 150 KM engine to kW and HP
150 KM engine: kW = 150 x 0.7355 = 110.3 kW; HP = 150 x 0.9863 = 147.9 HP; W = 110 325 W. Reverse: 110 kW = 149.6 KM = 147.6 HP = 110 000 W. A 300 HP V8 engine: kW = 300 x 0.7457 = 223.7 kW = 304.2 KM = 223 710 W. A 200 kW electric motor = 272 KM = 268.2 HP = 200 000 W.
Frequently asked questions
What is the difference between KM and kW?
KM (metric horsepower, also PS or CV) is a historical unit used in European automotive engineering. 1 KM = 0.7355 kW. Kilowatt (kW) is the SI unit and is legally required in the EU for vehicle power ratings. Conversion: kW = KM x 0.7355; KM = kW x 1.3596.
What is HP and how does it differ from KM?
1 SAE HP = 0.7457 kW, while 1 metric KM = 0.7355 kW. HP is therefore about 1.4% larger than KM. For 100 KM: 98.6 HP. For 100 HP: 101.4 KM. SAE HP is the standard in the USA and Canada; metric KM (PS) dominates in Europe.
How many kW does a typical passenger car have?
City cars: 50-85 kW (68-115 KM). Mid-range: 90-150 kW (122-204 KM). Sports cars: 200-400 kW (272-544 KM). Premium EVs: 300-600+ kW. For reference: VW Golf 1.5 TSI 110 kW (150 KM); BMW M3 375 kW (510 KM).
Why does the EU require power to be stated in kW?
EU directives on units of measurement require the use of SI units. kW is an SI unit (1 kW = 1000 J/s), while KM and HP are non-SI units. Registration documents and type approvals in the EU must state power in kW.
How do I convert KM to kW without a calculator?
Quick approximation: multiply KM by 0.74. More precisely: multiply by 3/4 (0.75). For 100 KM: 74-75 kW (exact: 73.55 kW). Reverse: multiply kW by 1.36. For 100 kW: about 136 KM (exact: 135.96 KM).
How many watts is 1 metric KM and where does the definition come from?
1 KM = 735.4988 W. The definition comes from: 75 kgf x 9.80665 m/s2 x 1 m = 735.4988 N*m/s = 735.4988 W. James Watt defined the original HP as the power of a mine horse: 33,000 ft-lbf/min = 745.7 W (1 SAE HP).
Are watts (W) used to describe engine power?
In engineering, kW (kilowatts) is preferred because watts are too small a unit for engines. A 100 KM engine is 73,550 W = 73.55 kW. Watts are common for electrical appliances (light bulbs, chargers); engines are rated in kW or KM.
What is the difference between SAE HP, DIN HP and metric KM?
SAE HP (USA) = 745.6999 W. Metric KM (PS, CV, DIN HP) = 735.4988 W. UK mechanical HP = 745.6999 W (same as SAE). Electric KM = 746 W (used for electric motors in some systems). This converter uses SAE HP and metric KM.
How does engine power affect fuel consumption?
Having a more powerful engine does not automatically mean higher fuel consumption - the key is the working load. A 150 kW engine driving at constant speed may use less fuel than an 80 kW engine under full load. Modern downsizing (small turbocharged engines) combines high power with moderate fuel consumption.
Does the converter treat mechanical and electrical power the same?
Yes - kilowatts and other power units are independent of the energy source. 100 kW from a combustion engine equals 100 kW from an electric motor. The difference lies in efficiency: an electric motor achieves 85-95% efficiency, a petrol engine 25-40%. The converter converts units, not system losses.
Results are for informational purposes only. Conversion factors follow international definitions: 1 metric KM = 735.4988 W, 1 SAE HP = 745.6999 W. Engine power stated by manufacturers may be measured by different methods (DIN, SAE net, SAE gross) and may differ slightly from the converted values.