Electrical · Problem-solving calculator
AC Power Calculator
Estimate real and apparent AC power from voltage, current, power factor, and single- or three-phase configuration.
- Free to use
- Runs in your browser
- Level B · Industry formula
- Last reviewed 2026-08-17
Calculator guide
What this calculator helps you solve
Estimate real and apparent AC power from voltage, current, power factor, and single- or three-phase configuration.
Inputs explained
- AC system — enter the value that applies to your operation or scenario.
- Voltage (V) — enter the value that applies to your operation or scenario.
- Current (A) — enter the value that applies to your operation or scenario.
- Power factor (0–1) — enter the value that applies to your operation or scenario.
Formula and methodology
Worked example
A 480 V, 100 A, three-phase load at 0.90 power factor uses about 74.82 kW of real power and 83.14 kVA of apparent power.
How to interpret the result
Use the result for load and energy scenarios after confirming whether entered voltage is the appropriate line voltage for the system. Motors and other equipment can require additional current, efficiency, starting, harmonic, and code considerations.
What to keep in mind
- The three-phase formula assumes a balanced system and line-to-line voltage.
- Power factor is entered as a decimal between 0 and 1.
- This is not a conductor, breaker, transformer, or protective-device sizing calculator.
Review approach
This calculator uses deterministic arithmetic and performs the calculation locally in your browser. Its value comes from combining operational inputs into a decision-oriented result rather than returning a one-line conversion.
Review standard: Level B · Industry formula. How calculator reviews work.
Frequently asked questions
What decision can this calculator support?
Use the result for load and energy scenarios after confirming whether entered voltage is the appropriate line voltage for the system. Motors and other equipment can require additional current, efficiency, starting, harmonic, and code considerations.
How is the result calculated?
Single-Phase kW = V × I × PF ÷ 1000; Three-Phase kW = √3 × V × I × PF ÷ 1000.
Are the assumptions universal?
No. Operational, regulatory, technical, and industry assumptions vary. Use values that apply to your situation and verify professional or regulatory requirements where relevant.
Does CalculateMeasure store the values I enter?
The calculation runs in your browser and does not require sending the entered calculator values to a server to produce the result.