Power & phase
Single-Phase Power Calculator
Single-phase apparent power equals voltage multiplied by current. Real power is apparent power multiplied by power factor.
Calculate real power, apparent power, and current for a single-phase AC circuit.
Calculated result
Single-phase power result
Calculating…
Calculated locally in your browser
Planning math only. Verify equipment specifications and installation requirements separately.
What this calculator returns
The result keeps real and apparent power separate so the PF assumption remains visible.
Formula and variables
The calculation runs entirely in your browser. Static formulas, definitions, examples, and tables remain readable without JavaScript.
S = V × I; P = V × I × PF.
- P
- Real power, in watts or kilowatts.
- S
- Apparent power, in volt-amperes or kilovolt-amperes.
- V
- RMS voltage; line-to-line voltage in three-phase modes.
- I
- Line or circuit current, in amperes.
- PF
- Power factor, expressed as a ratio from greater than zero through one.
- Q
- Reactive power, in volt-amperes reactive.
S is apparent power in VA and P is real power in W.
Worked example
| Input | Value |
|---|---|
| Voltage | 240 V |
| Current | 10 A |
240 V × 10 A × PF 0.8 = 1.92 kW and 2.4 kVA.
Reference table
| System | Apparent power | Real power | Voltage entry |
|---|---|---|---|
| DC | S = V × I | P = V × I | Circuit voltage |
| Single-phase AC | S = V × I | P = V × I × PF | RMS circuit voltage |
| Balanced three-phase AC | S = √3 × VLL × I | P = √3 × VLL × I × PF | Line-to-line RMS voltage |
Frequently asked questions
What is the difference between kW and kVA?
kW is real power, while kVA is apparent power. They are equal only when power factor is 1.
Can I use 240 volts for a single-phase load?
Yes, when 240 volts is the actual voltage across that load. Enter the load voltage rather than assuming a nominal system value.
Assumptions and limitations
- Steady-state sinusoidal planning model.
- No branch-circuit or protection sizing.
Method and sources
Review the electrical formulas, calculation methodology, and reference tables for the references most relevant to this calculation. The broader technical sources index records source scope and verification. Last reviewed .