Watts to kVA Calculator
Convert real power in watts (W) to apparent power in kilovolt-amps (kVA). Enter the real power and the power factor, and press Calculate to get the apparent power in kilovolt-amps using S(kVA) = P(W) / (1000 × PF). Everything runs locally in your browser.
Enter real power in watts
Type the real power P in watts — the power that actually does work, such as a heater, motor shaft output, or the nameplate wattage of a device. Scientific notation like 5e-3 is accepted.
Enter the power factor
Type the power factor PF, a number between 0 (exclusive) and 1 that describes how much of the apparent power actually does work. Use 1 for purely resistive loads like heaters; motors and electronics typically sit well below 1. Check the nameplate or measure it for accuracy.
Press Calculate, read kVA
Apparent power appears in kilovolt-amps instantly. Press Clear to reset the fields and start over. Every value is computed in your own browser tab.
How to convert watts to kVA
- What is the watts to kVA formula?
- The apparent power S in kilovolt-amps (kVA) is equal to the real power P in watts (W), divided by 1000 times the power factor PF: S(kVA) = P(W) / (1000 × PF).
- Can you give a worked example?
- A 2000 W load at a power factor of 0.8 draws S = 2000 / (1000 × 0.8) = 2.5 kVA. At unity power factor the conversion simplifies: 1000 W at PF 1 is exactly 1 kVA, and a 3500 W motor at PF 0.7 needs 5 kVA of apparent power.
- Why are watts and kVA different?
- Watts is real power — the part that actually performs work. kVA is apparent power — the total flow the system must carry. The power factor (between 0 and 1) is their ratio, lowered by reactive loads such as motors and transformers, so the kVA figure is never smaller than the wattage implies.
- What power factor should I use?
- Use 1 only for purely resistive loads. Inductive and electronic loads run below 1 — read the equipment nameplate or measure it with a power analyzer. A power factor of 0 makes the conversion undefined, so it is not accepted here. Do not guess a typical value for anything that needs to be accurate.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Results are ideal-circuit values; verify real installations with a multimeter.