Single Phase Power Calculator
Calculate single phase power step by step: P = V × I × PF; S = V × I.
In short
Formula: P = V × I × PF; S = V × I.
Real power
2,070 W
- Apparent power
- 2,300 VA
- Reactive power
- 1,002.5468 var
- Kilowatts
- 2.07 kW
What this calculator does
Calculate single phase power step by step: P = V × I × PF; S = V × I. Worked example, questions and limitations included.
Use it to turn Voltage (RMS), Current (RMS), Power factor into a checked result you can compare, copy, or rerun with different assumptions.
The page shows the formula, a numeric worked example, and the assumptions that affect this electrical calculation.
Inputs and what they mean
- Voltage (RMS)
- — number value.
- Current (RMS)
- — number value.
- Power factor
- — number value.
How to use it
- Enter each value in the unit shown next to the box (use the unit converter first if your numbers are in other units).
- Check the breakdown to see every intermediate step.
- Read the limitations before relying on the result.
Formula
Use RMS voltage and current.
Power factor between 0 and 1; use 1 for a purely resistive load.
Result is real power in watts.
P = V × I × PF; S = V × I.
Inputs used: Voltage (RMS), Current (RMS), Power factor.
Worked example
230 V, 10 A, PF 0.9
- S = 230 × 10 = 2,300 VA.
- P = 2,300 × 0.9 = 2,070 W.
Reading the result
The headline figure is the main answer. Any breakdown underneath shows the parts that make it up, so you can check the working and see what changes when you adjust an input.
Limitations and assumptions
- Sinusoidal supply assumed.
- Uses a single steady power factor.
- Efficiency of the driven machine is not included.
- Results are estimates for planning and learning. Real designs, installations and bids must be checked by a qualified, licensed professional against the codes that apply where you work.
- The result depends on the values you enter for this single phase power calculator; it does not supply missing rates, rules, prices, dates, or assumptions for you.
Common questions
What power factor should I enter?
Use the nameplate or a measured value. Resistive heaters are close to 1; motors are often lower, especially lightly loaded.
Why is watts less than VA?
With PF below 1, part of the current does no useful work, so real power is smaller than apparent power. Check the formula, example, and limitations on this page before using the result for a real electrical decision.
Is this for 120 V as well?
Yes — enter any single-phase voltage. Check the formula, example, and limitations on this page before using the result for a real electrical decision.
How do I use the Single Phase Power Calculator?
Enter the required values for Voltage (RMS), Current (RMS), Power factor. The calculator applies the formula on this page and shows the main result with any supporting breakdown so you can check the arithmetic.
What formula does the Single Phase Power Calculator use?
P = V × I × PF; S = V × I. The visible formula section above lists the calculation path and the edge cases the page handles, so the result can be checked without relying on the form alone.
Can the Single Phase Power Calculator be used for exact decisions?
Use it as a calculation aid, not as a substitute for checking the underlying rule, contract, policy, or professional advice that applies to your situation. When a result depends on local rules, personal details, prices, or dates, enter those values yourself and confirm them before acting.
Related tools
Calculate electrical power step by step: P = V × I = I² × R = V² ÷ R (DC or resistive AC using RMS values).
Calculate voltage divider step by step: Vout = Vin × R2 ÷ (R1 + R2).
Calculate resistance step by step: R = V ÷ I, or for a conductor R = ρ × L ÷ A (A in m²).