Torque
Power
Power from torque and rpm
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.
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.