How to convert 21 kW to horsepower
One kilowatt equals 1.34102 mechanical horsepower. For 21 kW:
21 kW × 1.34102 = 28.2 hp
Rounded, a 21 kW motor is rated at about 28 hp. European brochures often quote metric horsepower instead: 29 PS.
21 kW in other units
| Metric horsepower (PS) | 28.55 PS |
| Mechanical horsepower (hp) | 28.16 hp |
| Watts | 21,000 W |
| BTU per hour | 71,655 BTU/h |
What torque does 21 kW give?
Power and torque are linked by engine speed: torque (lb-ft) = hp × 5,252 ÷ rpm, or torque (Nm) = kW × 9,549 ÷ rpm. If 21 kW is produced at these speeds:
| Engine speed | Torque |
|---|---|
| 1,500 rpm | 134 Nm (99 lb-ft) |
| 2,500 rpm | 80 Nm (59 lb-ft) |
| 3,500 rpm | 57 Nm (42 lb-ft) |
| 4,500 rpm | 45 Nm (33 lb-ft) |
| 5,500 rpm | 36 Nm (27 lb-ft) |
| 6,500 rpm | 31 Nm (23 lb-ft) |
Running at 21 kW
A motor or heater running at 21 kW for one hour uses 21 kWh. At $0.17 per kWh that costs about $3.57 per hour.
21 kW as a charging rate
An EV charging at 21 kW adds 42 kWh (10–80% of a 60 kWh battery) in about 2 h 12 min, including roughly 10% charging losses.
Is 21 kW a lot?
The European A2 motorcycle licence is limited to 35 kW. For a car this is very little power.
Values around 21 kW
| kW | PS | hp |
|---|---|---|
| 17 kW | 23.11 PS | 22.80 hp |
| 18 kW | 24.47 PS | 24.14 hp |
| 19 kW | 25.83 PS | 25.48 hp |
| 20 kW | 27.19 PS | 26.82 hp |
| 21 kW | 28.55 PS | 28.16 hp |
| 22 kW | 29.91 PS | 29.50 hp |
| 23 kW | 31.27 PS | 30.84 hp |
| 24 kW | 32.63 PS | 32.18 hp |
| 25 kW | 33.99 PS | 33.53 hp |
Frequently asked questions
How many hp is 21 kW?
21 kW is 28.2 mechanical horsepower (28 hp rounded).
How many kW is 28 hp?
28 hp is 20.9 kW (hp × 0.7457).
How many PS is 21 kW?
21 kW is 28.55 metric horsepower (PS).
Is 21 kW a lot?
The European A2 motorcycle licence is limited to 35 kW. For a car this is very little power.
Last updated November 10, 2026