Torque to kW Calculator
Convert torque in newton-metres and RPM into kilowatts instantly.
This calculator converts torque in newton-metres and engine speed in RPM directly into power in kilowatts — the metric equivalent of the 5252 horsepower rule.
Torque to kW Formula
The constant 9549 comes from converting radians per second and newton-metres into watts (it equals 60 × 1000 ÷ 2π). If your torque is in pound-feet, convert first (1 lb-ft = 1.3558 Nm) or use the imperial torque to HP calculator.
How to Use This Calculator
- Enter torque in newton-metres.
- Enter engine speed in RPM.
- Read kilowatts instantly, with the horsepower equivalent shown below.
Worked Example
The Metric Power Equation Explained
Where the imperial world uses HP = (lb-ft × RPM) ÷ 5252, the metric system uses kW = (Nm × RPM) ÷ 9549. Both express the same physics — power equals torque times angular velocity. The 9549 constant converts RPM to radians per second (×2π÷60) and newton-metres to kilowatts (÷1000). Knowing both lets you move freely between a European dyno sheet in Nm/kW and a US one in lb-ft/HP.
When to Use Torque-to-kW
This is the go-to conversion for engineers and EV enthusiasts working in SI units, or anyone reading a European engine spec. Electric motors in particular are characterised by their torque-and-speed curve, so converting a stated torque at a given RPM into kilowatts gives the power figure directly comparable to a battery or charger rating.
Torque to kW at 4,000 RPM
| Torque (Nm) | Power (kW) | Approx. HP |
|---|---|---|
| 100 | 41.9 | 56 |
| 200 | 83.8 | 112 |
| 300 | 125.7 | 169 |
| 500 | 209.4 | 281 |
Frequently Asked Questions
Use kW = (Torque in Nm × RPM) ÷ 9549. You need both the torque and the RPM at which it occurs.
It converts newton-metres and RPM into kilowatts, derived from 60,000 ÷ 2π. It's the metric equivalent of the 5252 constant used with pound-feet.
Convert to newton-metres first by multiplying by 1.3558, or use our torque to HP calculator which works in imperial units.
No. Power depends on how fast the torque is delivered, so RPM is required.
Multiply kilowatts by 1.341 to get mechanical horsepower.