bhp to kW converter and A2 licence check
Type a power figure in bhp, PS or kW and get the other two. Add the bike’s weight, and its power before any restriction, to check it against the A2 licence limits.
46.0 bhp = 34.3 kW = 46.6 PS
The A2 licence check
| GOV.UK limit | Your bike | Result |
|---|---|---|
| Power, up to 35 kW | 34.30 kW | Within |
| Power to weight, up to 0.2 kW per kg | Add the weight | Not checked |
| Not derived from a bike of more than twice its power | Add the original power | Not checked |
Inside the limits checked so far. Add the missing figures to check the rest. GOV.UK's page doesn't say which weight the ratio uses, so we use the one you type.
A2 limits quoted from GOV.UK's bike categories and licence requirements: "Standard motorcycle up to 35 kW (and a power-to-weight ratio not more than 0.2 kW per kg), bike must not be derived from vehicle more than twice its power". Checked against GOV.UK on 30 October 2026. Factors from NIST's conversion tables (SP 811), read on 30 October 2026: 1 hp = 745.6999 W, 1 PS = 735.4988 W.
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How to use it
Type the power and pick its unit. The answer gives bhp, kW and PS together. For the A2 check, add the bike's weight in kilograms and, for a restricted bike, the power it made before it was restricted, in the same unit. Each of the three A2 limits gets its own line, so you can see which one a bike passes or misses.
The A2 limits
GOV.UK's table of licence categories gives three tests for an A2 bike: a top power, a top power to weight, and a limit on how far a restricted bike can have been cut back from its original power. The tool shows each figure as GOV.UK words it, quoted under the tool with the date we last checked it. We read the wording every night, and if GOV.UK changes it the tool says the limits are being re-checked. That way the numbers on this page never go out of date on their own.
One thing GOV.UK's page doesn't say is which weight the ratio uses. So the tool works with the weight you type, and tells you the ratio it worked out.
How it is worked out
| From | To kW | Example |
|---|---|---|
| bhp | × 0.7456999 | 47 bhp = 35.0 kW |
| PS | × 0.7354988 | 47.6 PS = 35.0 kW |
The factors come from NIST's tables of units, read on 30 October 2026: one horsepower is 745.6999 watts and one metric horsepower (PS) is 735.4988 watts. bhp (brake horsepower) is a horsepower figure, so it uses the horsepower factor. Power to weight is kW ÷ kg.
Before you buy
A tool can only work with the figures you give it. For a bike you're thinking of buying, get its power and weight from its paperwork, and check GOV.UK's bike categories and licence requirements page for the latest wording.
Written by Craig Fearn, Throttlefolio. Last updated .
Questions answered
How many bhp is 35 kW?
About 46.9 bhp, or 47.6 PS.
How do I convert bhp to kW?
Multiply by 0.7456999. 100 bhp is 74.6 kW. For PS, multiply by 0.7354988.
Where do the A2 limits come from?
From GOV.UK’s bike categories and licence requirements page. The tool quotes its wording and re-reads it every night.