Watts to kVA Calculator
Enter real power in watts and power factor to calculate apparent power in kVA instantly. Essential for sizing generators, UPS systems and transformers.
How do you convert watts to kVA?
Divide watts by the power factor and then by 1000: kVA = W ÷ (PF × 1000). A 1500 W load at PF 0.8 equals 1500 ÷ (0.8 × 1000) = 1.875 kVA. Because apparent power is always ≥ real power, a generator or UPS rated in kVA must be chosen based on this larger figure — not the watts alone.
Power factor represents the efficiency of power use in an AC circuit. Resistive loads (heaters, incandescent lamps) have PF = 1.0 so kVA = kW. Inductive loads (motors, transformers) typically have PF 0.7–0.95, meaning the apparent power is significantly higher than the real power.
Watts to kVA Conversion Table
| Watts (W) | PF 0.7 | PF 0.8 | PF 0.9 | PF 1.0 |
|---|---|---|---|---|
| 500 W | 0.714 kVA | 0.625 kVA | 0.556 kVA | 0.500 kVA |
| 1000 W | 1.429 kVA | 1.250 kVA | 1.111 kVA | 1.000 kVA |
| 1500 W | 2.143 kVA | 1.875 kVA | 1.667 kVA | 1.500 kVA |
| 2000 W | 2.857 kVA | 2.500 kVA | 2.222 kVA | 2.000 kVA |
| 5000 W | 7.143 kVA | 6.250 kVA | 5.556 kVA | 5.000 kVA |
| 10000 W | 14.29 kVA | 12.50 kVA | 11.11 kVA | 10.00 kVA |
Formula
Where: kVA = apparent power in kilovolt-amps, W = real power in watts, PF = power factor (0–1).
Alternatively expressed as: kVA = kW ÷ PF. If you already have kW, use the kW to kVA calculator directly.
Frequently Asked Questions
Use the formula kVA = W ÷ (PF × 1000). You need the power factor of your load. If unknown, 0.8 is a common conservative assumption for mixed AC loads.
Real power (watts) is the energy actually consumed as heat, light or work. Apparent power (kVA) is the total power the supply delivers, including the reactive portion that flows back and forth in inductive circuits. A generator must be sized to the apparent power, not just the real power.
Power factor is the ratio of real power to apparent power (PF = kW ÷ kVA). Without it, you cannot determine how much of the apparent power is doing useful work. A purely resistive load (PF = 1) has kVA = kW, but a motor at PF = 0.8 needs 25 % more apparent power than its real-power rating.
It depends on the power factor. At PF 0.8: 2000 ÷ (0.8 × 1000) = 2.5 kVA. At PF 0.9: 2000 ÷ (0.9 × 1000) ≈ 2.22 kVA. At PF 1.0: 2000 ÷ 1000 = 2.0 kVA.
No. Apparent power (kVA) is always greater than or equal to real power (kW) because PF is always ≤ 1. If kVA equalled kW, the power factor would be 1.0, meaning a purely resistive load with no reactive component.