How this instrument works
A watt is a newton-metre of work delivered every second, coherent SI power built from nothing but base units, adopted by the same 1960 conference that formalised the modern metric system. A kilowatt is a thousand of them, the unit stamped on European and Asian electric-motor nameplates, EV powertrain specifications, generator ratings and industrial pump datasheets worldwide. It carries no ambiguity: 1 kW means exactly 1000 W everywhere it appears, with nothing left to interpretation.
Horsepower carries rather more baggage. James Watt coined it in the 1780s, estimating how much work a strong dray horse could sustain, and later engineers pinned the figure at exactly 550 foot-pounds per second — 745.6998715822702 W — a value now called mechanical or imperial horsepower and the one this page converts to. A separate metric horsepower, PS in German or CV in French, is defined instead as 75 kilogram-force metres per second, working out to 735.49875 W — smaller by about 1.4 percent, and the number still printed on continental European car brochures and some pump and compressor catalogues.
This calculator uses the mechanical definition, 1 kW = 1.3410220896 hp, because it is the figure that appears on North American motor nameplates, EV range and power comparisons, small-engine catalogues and SAE-referenced test data. A European car's 100 kW motor becomes 134.1 mechanical horsepower here, but the same car's own brochure, if it quotes metric horsepower instead, would print roughly 136 PS — a gap worth noticing before assuming two power figures from different sources describe the identical output.
- Enter your figure into the Kilowatts (kW) field; it opens at 50 kW, a plausible rating for a small industrial motor or compact EV.
- Read the Horsepower (hp) field beneath it — recalculated on every keystroke, using the mechanical (imperial) horsepower definition.
- Comparing against a European car brochure? Check whether it quotes PS (metric horsepower) rather than kW-derived hp — the two differ by about 1.4 percent.
- Going the other way, from horsepower to kilowatts, divide your hp figure by 1.3410220896, or multiply by 0.745699872.
- For a generator or pump nameplate, match the rating type — continuous, peak or intermittent — before comparing across brands; the unit conversion doesn't fix a mismatched rating basis.
Worked example — a 50 kW motor rated for a North American spec sheet
A compact electric drivetrain or mid-size industrial motor carries a manufacturer's continuous power rating of 50 kW on its European technical datasheet. Enter 50 into Kilowatts (kW) and Horsepower (hp) reads 67.0511044798 — the figure a North American distributor or trade publication would print alongside it, rounded in practice to about 67 hp.
Check that figure against a metric-horsepower conversion and it diverges slightly: 50 kW is 67.05 mechanical hp but roughly 68.0 PS, since metric horsepower is defined against a smaller watt-per-unit figure. The gap, under one and a half percent, rarely changes a buying decision, but it explains why the same motor can show two different 'horsepower' numbers depending on which brochure printed it.
Questions
Is 1.3410220896 an exact conversion factor?
It is exact, to the twelve significant figures shown. Mechanical horsepower is defined as precisely 550 foot-pounds-force per second, which multiplies out to 745.6998715822702 W using the same defined pound, foot and standard-gravity values behind every imperial force unit. Dividing 1000 W by that figure gives 1.34102208959503…, a repeating decimal truncated here at ten decimals — an error far smaller than any motor nameplate's stated tolerance.
What is metric horsepower, and why doesn't this page use it?
Metric horsepower — PS in German, CV in French, pk in Dutch — is defined as 75 kilogram-force-metres per second, equal to 735.49875 W, a genuinely different number from the 745.6998715822702 W behind mechanical horsepower. It remains the figure printed on most continental European car, motorcycle and small-engine brochures. This page converts to mechanical horsepower because that is the definition used on North American nameplates, EV specifications and SAE-referenced power tests; if your source figure is PS rather than kW, multiply it by 0.73549875 to reach kW first.
Why do EV manufacturers list kW instead of horsepower?
Because kilowatts are what the motor and battery system are actually engineered around — charging rates, continuous and peak output, and regenerative braking capacity are all specified in kilowatts internally, and horsepower is added afterward purely for buyers used to combustion-engine spec sheets. Some manufacturers publish only kW, especially outside North America; this conversion exists mainly to translate those figures for markets and publications that still expect a horsepower number.
Does horsepower measure the same thing as torque?
No, though the two are related. Torque is a twisting force at one instant, typically in newton-metres or foot-pounds; power — kilowatts or horsepower — is how quickly that torque can do work, which depends on rotational speed as well as torque itself. Two motors can share an identical peak-torque figure yet differ enormously in horsepower if one reaches that torque at a much higher rpm. A single kW-to-hp conversion says nothing about a motor's torque curve at all.
How much power is 50 kW in everyday terms?
Enough to lift a small car's weight — roughly 1200 kg — about four metres straight up every second, or to run around 25 typical 2-kilowatt electric kettles simultaneously. It sits in the range of a small city-car's electric motor, a large residential backup generator, or a mid-size industrial pump. For scale, a healthy adult cyclist sustains perhaps 0.2 to 0.4 kW, so 50 kW represents well over a hundred cyclists' combined output.
How many decimal places should I keep for a spec sheet?
One, at most, and often a whole number is plenty. Motor and engine power ratings already carry manufacturing and test tolerances of a few percent, so 67.0511044798 hp and 67 hp describe the same real-world motor. Full precision matters only while chaining several conversions together, where rounding early can compound into a visible error by the final step — round once, at the end, to whatever precision the source data actually supports.