kW to BHP Converter

Every car sold in Europe has its power stamped on the registration document in kilowatts, and almost nobody thinks in kilowatts. If you're staring at "P.2: 147 kW" and trying to work out whether that's the 200 bhp car you thought you were buying, this is the conversion — and the answer is slightly annoying.

kW to BHP Conversion Chart

Common power ratings with brake horsepower and metric horsepower side by side. The third column is the number that usually ends up on the boot lid in Germany, France and Italy; the second is the number a UK magazine will print.

What the "Brake" in Brake Horsepower Actually Means

The word is a leftover from the Prony brake, an 1821 device that clamped a friction band around a spinning flywheel and measured the force needed to hold it back. Load the engine until it settles at a steady speed, read the force and the arm length, and you've torque — and from torque and rpm, power.

Modern engine dynamometers use water brakes or eddy-current absorbers instead of a wooden shoe, but the principle hasn't changed: the engine is bolted to a stand, the load is applied at the crankshaft, and nothing between the flywheel and the tarmac gets a chance to eat any of the reading. That's why brake horsepower is always higher than what a rolling road reports.

bhp, hp, PS and whp in one table

The row that trips people up is the second one. As a unit, bhp and hp are identical — both are 745.699872 watts. The letters don't change the size of the number; they only hint at where the measurement was taken. If you want the full breakdown, our guide to hp, bhp, PS and kW compared works through each standard.

The 1.4% Trap: Why the Badge Says 200 and the Maths Says 197

Metric horsepower was defined as the power needed to lift 75 kilograms one meter in one second — 735.49875 W. Mechanical horsepower came from 550 foot-pounds per second — 745.699872 W. They were invented in different countries for different measuring systems, and nobody ever reconciled them.

The practical result is that PS figures run about 1.39% higher than bhp figures for the same engine. Manufacturers pick round PS numbers for marketing, so the mismatch shows up constantly:

• 147 kW → 200 PS on the badge, 197 bhp in the conversion
• 228 kW → 310 PS on the badge, 306 bhp in the conversion
• 375 kW → 510 PS on the badge, 503 bhp in the conversion

None of these cars is underperforming. They're the same engines described with two different yardsticks. When a used-car advert quotes a suspiciously round bhp number — "200 bhp" for a car whose V5C says 147 kW — the seller has simply copied the PS badge and swapped the letters.

Which Standard Was That kW Figure Measured To?

Two engines can both be honestly rated "150 kW" and still not be comparable, because the rating standard sets how much of the engine's own equipment has to be attached while it runs. This is the part most converters ignore, and it matters more than the arithmetic.

ECE R85 and SAE J1349 net figures land close enough that a straight unit conversion between them is fair. Comparing either against a 1969 gross rating isn't — see how horsepower is measured for the full story on correction factors.

Where the kW Figure Lives on Your Paperwork

If you're checking a car before buying, work from the document rather than the advert:

• UK V5C — section 4, field P.2 "Maximum net power", always in kW.
• EU Certificate of Conformity — entry 27, again in kW, with the rated speed in rpm beside it.
• Insurance quote forms — most UK and Irish insurers key off the kW value, not the advertised bhp, which is why two "200 bhp" cars can quote differently.
• Vehicle tax in kW-banded countries — Germany, Austria, Poland, Croatia and several others price bands from the kW number, so rounding the conversion the wrong way can move you a band.

Reading kW Ratings on Electric Cars

The conversion arithmetic is the same, but an EV kilowatt figure and an engine kilowatt figure don't always describe the same thing. UN Regulation 85 defines two separate numbers for electric drivetrains: maximum net power, a short peak, and maximum 30-minute power, what the motor can hold continuously without thermal derating.

Brochures quote the peak. A dual-motor EV advertised at 350 kW (469 bhp) may only sustain a fraction of that after a couple of hard launches, which is why EV drag times fall off on repeat runs in a way combustion cars don't. When you compare an EV against a gasoline car, check whether you're holding peak against sustained. Our kW per tonne calculator is the fairer comparison for real-world feel.

Converting the Other Direction

Going from horsepower back to kilowatts is handled by the bhp to kW converter. If your source figure is plain "hp" rather than "bhp", the HP to kW calculator and kW to HP calculator use the same factor. For metric horsepower use kW to PS, and to move directly between the two horsepower standards see bhp to PS. Every unit at once lives in the horsepower unit converter.