Volts to Watts Calculator
Convert voltage in volts (V) to power in watts (W). Select the current type — DC, AC single phase or AC three phase — enter the voltage in volts, the current in amps and, for AC, the power factor, then press Calculate to get the power in watts. Everything runs locally in your browser.
Select the current type
Pick DC for direct current, AC - Single phase for ordinary mains circuits, or AC - Three phase for three-phase supplies. The power-factor field appears only for the AC modes.
Enter volts, amps and power factor
Type the voltage in volts and the current in amps. For AC modes also enter the power factor between 0 and 1 (0.8 to 1 is typical for motor and heater loads). Enter 1 for a purely resistive AC load.
Press Calculate, read watts
The result appears in watts (W), shown with at most 10 significant digits. Copy the result to your clipboard, or press Reset to clear everything and start over.
Volts to watts calculation
- How do you convert volts to watts (DC)?
- The power P in watts (W) is equal to the voltage V in volts (V), times the current I in amps (A): P(W) = V(V) × I(A). For example, a device on a 12 V supply drawing 2.5 A consumes 12 × 2.5 = 30 W.
- How do you convert volts 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). A 120 V circuit drawing 10 A at PF 0.9 delivers 0.9 × 10 × 120 = 1080 W.
- How do you convert volts to watts for AC three phase?
- The power P in watts (W) is equal to square root of 3 times the power factor PF times the phase current I in amps (A), times the line to line RMS voltage VL-L in volts (V): P(W) = √3 × PF × I(A) × VL-L(V) ≈ 1.732 × PF × I(A) × VL-L(V). This calculator multiplies by √3 and treats the voltage you enter as line-to-line. A 400 V, 5 A, PF 0.85 load is √3 × 0.85 × 5 × 400 ≈ 2944.49 W.
- Why does the calculator want a power factor, and why only between 0 and 1?
- In AC circuits with motors, transformers or electronics, current and voltage are not in phase, so real power is lower than V × I. The power factor is the ratio of real power to apparent power and lies between 0 and 1 — a value outside that range cannot describe a passive load, so it is rejected as an input error.
- What about line to neutral three-phase voltage?
- With line to neutral voltage the three-phase formula becomes P(W) = 3 × PF × I(A) × VL-N(V). This calculator uses the line-to-line variant (√3 × PF × I × VL-L); for a balanced star supply VL-L = √3 × VL-N, which makes both forms agree.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Copy result uses your clipboard only. Values are ideal steady-state results for balanced loads; verify real installations with a multimeter or power analyzer.