kVA to Watts Calculator — Apparent to Real Power | Ampstowatt Guide
Real vs apparent power
Watts, VA, kVA, and power factor shown as one relationship
These conversions depend on the difference between real and apparent power, so the power triangle makes the formula easier to trust.
Quick answer
Use this calculator to separate real watts from apparent power.
AC equipment can draw VA or kVA that is higher than usable watts. Power factor explains the difference and is critical for generators, UPS systems, motors, and transformers.
Inputs to check before calculating
- Use nameplate VA, kVA, or amperage where available.
- Enter a realistic PF for motors, compressors, UPS systems, and generators.
- Account for startup surge separately from running watts.
- Compare real watts with equipment output ratings.
Example: generator output
A 5 kVA generator at 0.80 power factor can supply about 4,000 watts of real power. Always compare calculator output with the generator nameplate and startup surge requirements.
Best use cases
- Generator planning
- UPS load estimates
- PF-adjusted watts
- single-phase AC load planning with clear unit labels.
Common mistake to avoid
Do not treat kVA as kW unless the power factor is 1.00.
How to use the result
Use the result to avoid undersizing generators, UPS units, and AC power equipment.
Calculator output is a planning estimate. Final breaker sizing, wire gauge, derating, voltage-drop limits, equipment protection, and code compliance should be verified with manufacturer documentation and a qualified electrician or engineer.
For the broad formula, reference table, and breaker planning context, start with the main Amps to Watts Calculator.