HP to kVA Calculator
Convert horsepower to kVA for motor, generator and transformer sizing: kVA = HP × 746 ÷ (PF × Eff × 1,000). Includes power factor and motor efficiency.
APPARENT POWER
9.75 kVA
WATTS
7,460 W
FORMULA
kVA=(HP×746)/(PF×Eff×1000)
💡 How to Convert HP to kVA
To convert horsepower to kVA, multiply the HP by 746 to get watts, divide by the power factor and the motor efficiency, then divide by 1,000. This gives the running apparent power the motor draws from the supply: the figure to compare with generator and transformer kVA ratings.
HP to kVA formula
Example: 10 HP, PF 0.85, Eff 0.9 → 7,460 ÷ (0.85 × 0.9 × 1,000) = 9.75 kVA
Worked examples
- 5 HP pump (PF 0.85, Eff 0.9): 3,730 ÷ 765 = 4.88 kVA running.
- 25 HP compressor (PF 0.85, Eff 0.9): 18,650 ÷ 765 = 24.4 kVA running.
- Small 2 HP motor with lower efficiency (PF 0.8, Eff 0.8): 1,492 ÷ 640 = 2.33 kVA.
HP to kVA table
| HP | Output kW | kVA (PF 0.85, Eff 0.9) | kVA (PF 0.8, Eff 0.85) |
|---|---|---|---|
| 1 | 0.75 | 0.98 | 1.1 |
| 2 | 1.49 | 1.95 | 2.19 |
| 3 | 2.24 | 2.93 | 3.29 |
| 5 | 3.73 | 4.88 | 5.49 |
| 7.5 | 5.59 | 7.31 | 8.23 |
| 10 | 7.46 | 9.75 | 10.97 |
| 15 | 11.19 | 14.63 | 16.46 |
| 20 | 14.92 | 19.5 | 21.94 |
| 25 | 18.65 | 24.38 | 27.43 |
| 30 | 22.38 | 29.25 | 32.91 |
| 50 | 37.3 | 48.76 | 54.85 |
| 75 | 55.95 | 73.14 | 82.28 |
| 100 | 74.6 | 97.52 | 109.71 |
Sizing a generator for a motor
The running kVA is only part of the story. Starting a motor directly on line commonly draws about 6–8 times its full-load current for a few seconds, and the generator must supply that surge without its voltage collapsing. Generator manufacturers publish motor-starting kVA capability for this reason, and the generator you need is often several times the motor's running kVA unless a soft starter or variable-frequency drive is used. Confirm with the generator supplier's sizing tool or datasheet.
Which horsepower?
These calculators use 1 HP = 746 W, the standard mechanical (imperial) horsepower (more precisely 745.7 W). Metric horsepower (PS or CV), used on some European and Asian equipment, is 735.5 W. Motor nameplate horsepower is the output at the shaft; the electrical power drawn is higher because of motor losses, which is why efficiency appears in the formulas.
Typical values: small single-phase motors often run at 70–85% efficiency and a power factor of 0.7–0.85; larger three-phase premium-efficiency motors exceed 90% efficiency with power factors around 0.85–0.9 at full load. Both efficiency and power factor drop when a motor is lightly loaded. The nameplate is the best source.
Related conversions: kVA to HP · HP to amps · kW to kVA