Enter the torque in Newton-meters and the RPM into the calculator to determine the power in kilowatts. This calculator helps in converting rotational mechanical power measurements from RPM and torque to kilowatts.
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RPM to kW Formula
Mechanical power equals torque multiplied by angular velocity. The constant 9549.3 consolidates two unit conversions: RPM to rad/s (multiply by 2π/60) and watts to kilowatts (divide by 1000). Combined: 60,000 / (2π) = 9549.3.
P (kW) = (T (Nm) * RPM) / 9549.29677
Variables:
- P = power in kilowatts (kW)
- T = torque in Newton-meters (Nm)
- RPM = rotational speed in revolutions per minute
| RPM | 50 Nm | 100 Nm | 200 Nm | 500 Nm | 1,000 Nm |
|---|---|---|---|---|---|
| 500 | 2.62 | 5.24 | 10.47 | 26.18 | 52.36 |
| 750 | 3.93 | 7.85 | 15.71 | 39.27 | 78.54 |
| 1,000 | 5.24 | 10.47 | 20.94 | 52.36 | 104.72 |
| 1,500 | 7.85 | 15.71 | 31.42 | 78.54 | 157.08 |
| 2,000 | 10.47 | 20.94 | 41.89 | 104.72 | 209.44 |
| 3,000 | 15.71 | 31.42 | 62.83 | 157.08 | 314.16 |
| 5,000 | 26.18 | 52.36 | 104.72 | 261.80 | 523.60 |
| * P(kW) = T(Nm) x RPM / 9549.3. Values rounded to 2 decimal places. | |||||
Power by Application
Real machines operate across predictable RPM and torque bands. Higher torque at lower RPM is the signature of gear motors and hydraulic drives. Higher RPM at lower torque is typical of centrifugal fans, machine tool spindles, and combustion engines at peak power.
| Machine Type | Typical RPM | Typical Torque (Nm) | Typical Power (kW) |
|---|---|---|---|
| Gear motor (conveyor/mixer) | 200-600 | 500-5,000 | 10-150 |
| IEC 4-pole induction (50 Hz) | 1,450-1,480 | 50-1,000 | 7.5-150 |
| IEC 2-pole induction (50 Hz) | 2,900-2,950 | 25-500 | 7.5-150 |
| Servo motor | 2,000-4,000 | 5-50 | 1-15 |
| Diesel generator set (50 Hz) | 1,500 | 637-1,910 | 100-300 |
| Petrol engine at peak power | 5,500-7,000 | 150-250 | 85-185 |
| Industrial hydraulic motor | 50-500 | 1,000-10,000 | 5-300 |
| * IEC 4-pole synchronous speed = 1,500 rpm (50 Hz). Slip of 1.5-3% yields nominal 1,450-1,480 rpm. Diesel gen torque: T = 9549.3 x kW / 1500. | |||
How to Calculate Power from RPM and Torque
- First, determine the torque (T) in Newton-meters.
- Next, determine the rotational speed (RPM).
- Multiply torque by RPM and divide by 9549.3 to get power in kilowatts.
- Check your result with the calculator above.
Example Problem:
Torque (T) = 500 Newton-meters, RPM = 1500 revolutions per minute
P = (500 x 1500) / 9549.3 = 750,000 / 9549.3 = 78.54 kW
