Source This Page
Convert Nm to kW from torque and RPM using kW = Nm × RPM ÷ 9,549, or work backward from kW to Nm or RPM, with lb-ft, hp and PS units too.
Nm to kW Formula
Use torque and rotational speed at the same shaft and operating point to calculate mechanical shaft power. Torque alone does not determine power. P = Tω does not require an efficiency factor; electrical input power or power at a different shaft needs separate efficiency or loss information.
P = (T × 2 π × RPM) / (60 × 1000) (kW)
Variables:
- P is power in kilowatts (kW)
- T is torque in newton-meters (Nm)
- RPM is rotational speed in revolutions per minute
Tip: A handy shortcut is kW ≈ T × RPM / 9550 (because 9550 ≈ 60×1000 / 2π).
| Torque (Nm) | Power (kW) |
|---|---|
| 5 | 0.785 |
| 10 | 1.571 |
| 15 | 2.356 |
| 20 | 3.142 |
| 30 | 4.712 |
| 40 | 6.283 |
| 50 | 7.854 |
| 75 | 11.781 |
| 100 | 15.708 |
| 125 | 19.635 |
| 150 | 23.562 |
| 200 | 31.416 |
| 250 | 39.270 |
| 300 | 47.124 |
| * Rounded to 3 decimals using kW = N·m × RPM × 2π / 60000. Assumed RPM: 1500. The 9550 denominator is only a rounded shortcut. At 1500 RPM: 1 N·m ≈ 0.157080 kW. | |
How to Calculate kW from Nm
- Note the torque T in newton-meters and the speed RPM.
- Apply
kW = (T × 2π × RPM) / (60 × 1000)or the shortcutkW ≈ T × RPM / 9550. - Compute power in kilowatts and verify with the calculator above.
Example: With T = 120 Nm at 1500 RPM, power ≈ 120 × 1500 / 9550 = 18.85 kW.
