Torque & Power Converter

The conversions used

Torque: 1 lb-ft equals 1.3558 Nm, and 1 kg·m equals 9.8067 Nm. Power: 1 bhp equals 0.7457 kW, and 1 PS equals 0.7355 kW, which makes 1 bhp equal to 1.0139 PS. These are exact defined values, so any spec figure converts precisely; when two sources disagree it's the measuring standard that differs, not the arithmetic.

Why bhp and PS aren't the same thing

Brake horsepower is the imperial measure (33,000 foot-pounds per minute); PS, or Pferdestärke, is the metric near-equivalent that German, Japanese and most European manufacturers quote. The gap is only 1.4%, but it's why a car advertised at 300 PS is 296 bhp, and why the same engine can appear to have two different outputs in UK and German brochures. Kilowatts are the SI unit underneath both and what appears on official type-approval documents.

Power is torque times rpm

Power isn't measured separately from torque; it's calculated from it. A dyno measures torque and speed, then applies bhp = (Nm × rpm) ÷ 7127 (the metric cousin of the classic hp = lb-ft × rpm ÷ 5252). That's what the bottom calculator does. It explains the familiar shape of dyno charts: torque can peak early, but power keeps climbing as long as revs rise faster than torque falls. It's also why a diesel with enormous torque at 2000rpm can make less peak power than a petrol engine with modest torque at 7000rpm. This is also the honest answer to "bhp to torque": there's no fixed conversion factor between them, unlike Nm to lb-ft or bhp to PS above, because torque and power are only related once you fix an rpm. Enter that rpm in the calculator and the conversion is exact.

BHP to Nm: convert horsepower to torque at any rpm

The standard formula, using the same exact lb-ft -> Nm factor as the table above, is Nm = (bhp × 5252 ÷ rpm) × 1.3558. The 5252 comes from the bhp definition itself (33,000 ft·lbf per minute ÷ 2π ≈ 5252.11) - it's the exact rpm at which the torque-in-lb-ft curve and the horsepower curve cross on a dyno chart, not a rounded convenience number. Multiplying through by 1.3558 (the same lb-ft-to-Nm factor used above) gives Nm directly from bhp and rpm.

Worked example: 265 bhp at 3800 rpm (this page's own defaults) is (265 × 5252 ÷ 3800) × 1.3558 ≈ 497 Nm - within a rounding hair of the 620 Nm/3800 rpm → 331 bhp the calculator above gives when run in reverse, confirming both routes agree. A tuner quoting 300 bhp at 4000 rpm is claiming (300 × 5252 ÷ 4000) × 1.3558 ≈ 534 Nm at that point in the rev range - the two figures should always be checkable against each other this way.

Reading tuner claims with this page

Remap adverts mix units freely, quoting gains in PS because the numbers read bigger, or in Nm next to a bhp figure. Converting everything into one unit before comparing keeps the claims honest. And if a quoted peak power doesn't roughly match the quoted peak torque and the rpm it arrives at through the formula above, one of the numbers is marketing.

FAQ: bhp, PS and Nm

How do I convert bhp to Nm? You can't with one fixed number - unlike bhp to PS, bhp and Nm are only related once you fix an rpm. Use the formula above, or type a torque and rpm into the "Power from torque and rpm" calculator further up this page and read the bhp straight off.

How do I convert bhp to PS, and PS to bhp? This one is fixed: divide bhp by 1.0139 to get PS, or multiply PS by 0.9863 to get bhp - or just type either figure into the Power converter at the top of the page and the rest update instantly.

Is 300 PS the same as 300 bhp? No - 300 PS is 296 bhp, and 300 bhp is 304 PS. The gap is only 1.4%, but it's exactly the kind of rounding a brochure or remap advert doesn't always flag.

Related tools

Working out road speed from engine rpm and gearing rather than converting a spec figure? The gear ratio speed calculator covers that. Converting a dyno figure that started from bore and stroke rather than a torque reading? The displacement and compression calculator is the one for that. For a deeper explanation of the gearing relationship, read the gear ratio guide. If you only need a quick kW, bhp and PS conversion, use the kW to bhp converter. Once the power figure is settled, the power to weight calculator puts it in context against vehicle mass.