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Kilowatts to Horsepower

For reading a European registration document.

Inputs
kW

The number of kilowatts to convert.

Horsepower (mechanical)
147.51hp
In metric horsepower (PS)
149.6PS
In watts
110,000W
50 kW
67.05hp
110 kW
147.51hp
220 kW
295.02hp
400 kW
536.41hp
hp = kW ÷ 0.7457 · PS = kW ÷ 0.73550

1 kW = 1.341022 hp

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Divide kilowatts by 0.7457 for mechanical horsepower or by 0.7355 for metric PS. 110 kW is 147.5 hp or 149.6 PS — the same engine, two conventions.

How to use kW to HP Converter

  1. Enter the kilowatts. From the registration document or type approval figure.
  2. Read both horsepower figures. Mechanical hp and metric PS, which differ by about 1.4%.

About converting kilowatts to horsepower

The kilowatt is the SI unit of power and the one that appears on European vehicle registration documents, type approval paperwork and increasingly on manufacturer specifications. Horsepower persists in conversation and in marketing because it is the unit people have an intuition for, which leaves owners routinely converting between a legal figure and a familiar one. The conversion has a wrinkle, because horsepower is not one unit. Mechanical horsepower is 745.7 watts and is what British and American sources mean. Metric horsepower is 735.5 watts and appears as PS in German markets, CV in French and Italian ones, and pk in Dutch. The difference is about one and a half percent, so the same engine can be honestly described as 148 hp or 150 PS depending on where the sentence is written. Both are shown here for that reason. Something worth understanding alongside the arithmetic is what the number refers to. Manufacturer power figures are measured at the crankshaft under controlled bench conditions, before the transmission takes its share. Power measured at the wheels on a rolling road is typically ten to fifteen percent lower, and the gap varies with drivetrain layout — an all-wheel-drive car loses more than a rear-wheel-drive one. Comparing a manufacturer figure against a dyno reading without accounting for that produces an apparent shortfall that is entirely expected.

Frequently asked questions

Why does my registration document use kW?
Because the kilowatt is the SI unit of power and EU type approval requires it. Horsepower is a legacy unit with more than one definition, which makes it unsuitable for a legal document — and several countries set vehicle tax bands directly on the kW figure.
Which horsepower should I quote?
Whichever your audience uses. British and American readers expect mechanical hp; German, French and Italian specifications typically use PS, CV or pk, all of which are metric horsepower. The gap is about 1.4%, so it rarely changes an impression.
How much power does a normal car have?
A small hatchback is usually 55 to 85 kW, roughly 75 to 115 hp. A mid-size family car runs 90 to 150 kW, and anything above 220 kW is firmly performance territory. Electric cars often quote higher figures because peak output is available instantly.
Is quoted power what reaches the wheels?
No. Manufacturer figures are measured at the crankshaft on a test bench, and transmission losses typically remove ten to fifteen percent before the power reaches the road. A dyno figure measured at the wheels is therefore always lower and is not directly comparable.

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