Volts to kW Calculator - Power from Voltage, Current and PF

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Standard electrical engineering formulas

Voltage is only one piece. To get kW you also need current, and for AC you need power factor. For three-phase systems, the sqrt(3) factor is part of the real power formula.

Formula at a glance

  • DC: kW = V x A / 1000
  • single-phase: kW = V x A x PF / 1000
  • three-phase: kW = 1.732 x V x A x PF / 1000

Field note: Voltage alone does not set power. A 230 V phone charger and a 230 V oven are very different loads.

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Volts to kW Calculator

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Formula

kW = (V × A) / 1000

How to use the Volts to kW Calculator

Use this as a fast electrical check, then compare the result with the nameplate, measured voltage and power factor. The formula is clean. Real panels, motors and UPS loads usually have one extra wrinkle.

Worked example

Example: 230 V, 15 A, PF 0.85 gives 2.93 kW single-phase. At 415 V three-phase, 15 A and PF 0.85 gives 9.17 kW.

Practical checks before you trust the number

  • Use line voltage and line current for three-phase.
  • If PF is unknown, a general motor estimate of 0.8 to 0.9 is common.
  • Resistive loads can usually use PF 1.

Common mistake

Voltage alone does not set power. A 230 V phone charger and a 230 V oven are very different loads.

Sources and references

Related calculators

Frequently Asked Questions

Single-phase: kW = (V × A × PF) ÷ 1000. Three-phase: kW = (√3 × V × A × PF) ÷ 1000. DC: kW = (V × A) ÷ 1000. Example: 230 V × 20 A × PF 0.9 ÷ 1000 = 4.14 kW.

kW = (V × A × PF) ÷ 1000 for single-phase. The PF accounts for the phase difference between voltage and current. Without PF, you'd compute kVA, not kW.

Single-phase: kW = (V × A × PF) ÷ 1000. Example: 230 V, 15 A, PF 0.85 → kW = (230 × 15 × 0.85) ÷ 1000 = 2.93 kW. Direct multiplication, divide by 1000 for kW.

Three-phase: kW = (√3 × V_line × A × PF) ÷ 1000. Example: 415 V, 20 A, PF 0.85 → kW = (1.732 × 415 × 20 × 0.85) ÷ 1000 = 12.2 kW. Use line voltage and line current.

Use the actual nameplate or measured PF. For residential mixed loads, 0.85 to 0.9. For motor-heavy loads, 0.7 to 0.85. For resistive heaters, PF = 1. The PF figure matters — using 1 instead of 0.7 overstates real power by 43%.

Single-phase, PF 1: kW = (240 × 30) ÷ 1000 = 7.2 kW. Single-phase, PF 0.85: kW = (240 × 30 × 0.85) ÷ 1000 = 6.12 kW. So a 30 A circuit at 240 V handles roughly 6 to 7 kW depending on PF.

Yes. Sum amps from each circuit, multiply by V and PF, get kW per circuit. Useful for energy auditing and load forecasting. Compare against the breaker rating to spot overloaded circuits.