Amps to Watts Calculator
Convert electric current in amps (A) to electric power in watts (W). Select the current type — direct current (DC), AC single phase, or AC three phase with line-to-line or line-to-neutral voltage — enter the current, voltage and power factor, and press Calculate to get power in watts, kilowatts and milliwatts. Everything runs locally in your browser.
Choose the current type
Pick Direct Current (DC) for batteries and electronics, Alternating Current (AC) - Single phase for household circuits, or Alternating Current (AC) - Three phase for motor and industrial circuits. Three phase also asks whether your voltage is line to line or line to neutral.
Enter current, voltage, power factor
Type the current and choose its unit (mA, A or kA), then the voltage and its unit (mV, V or kV). For AC modes also enter the power factor between 0 and 1 — use 1 for resistive loads like heaters and incandescent lamps. Scientific notation like 5e3 is accepted.
Press Calculate, read watts
Power appears in watts (W), kilowatts (kW) and milliwatts (mW) at once. Copy any of the three values to your clipboard, or press Reset to clear everything and start over.
How amps become watts
- How do you convert amps to watts (DC)?
- The power P in watts (W) is equal to the current I in amps (A), times the voltage V in volts (V): P(W) = I(A) × V(V). For example, 2 A at 12 V gives 2 × 12 = 24 W.
- How do you convert amps to watts for AC single phase?
- The power P in watts (W) is equal to the power factor PF times the phase current I in amps (A), times the RMS voltage V in volts (V): P(W) = PF × I(A) × V(V). For example, a 10 A load on 120 V at a power factor of 0.85 draws 0.85 × 10 × 120 = 1020 W.
- How do you convert amps to watts for AC three phase?
- With line-to-line voltage: P(W) = √3 × PF × I(A) × V(V) — 15 A at 480 V and PF 0.9 gives √3 × 0.9 × 15 × 480 ≈ 11223.7 W. With line-to-neutral voltage the factor 3 replaces √3: P(W) = 3 × PF × I(A) × V(V).
- What power factor should I use?
- Typical values: resistive loads such as heaters, ovens and incandescent lamps are about 1; fluorescent lamps about 0.95; induction motors about 0.85 at full load but only about 0.35 at no load; synchronous motors about 0.9. Do not use typical values for accurate calculations — measure or read the nameplate.
- Quick reference at 120 V (DC or unity power factor)
- 0.1 A → 12 W · 0.3 A → 36 W · 0.5 A → 60 W · 1 A → 120 W · 5 A → 600 W · 10 A → 1200 W · 15 A → 1800 W. Power in kilowatts is watts ÷ 1000 and in milliwatts is watts × 1000.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Copy buttons use your clipboard only. Results are ideal-circuit values; verify real installations with a multimeter.