Watts to volts calculator
Convert power in watts (W) to voltage in volts (V). Select the current type — DC, AC single phase, or AC three phase — enter the power, the current, and the power factor for AC circuits, then press Calculate to get the voltage. Everything runs locally in your browser.
Enter the values above and press Calculate to get the voltage in volts.
How the voltage is calculated
DC: voltage V in volts equals power P in watts divided by current I in amps — V = P / I.
AC single phase: RMS voltage equals power divided by the power factor times the phase current — V = P / (PF × I).
AC three phase, line to line: VL-L = P / (√3 × PF × I) ≈ P / (1.732 × PF × I).
AC three phase, line to neutral: VL-N = P / (3 × PF × I).
Choose the current type
Pick DC for direct current, "AC - Single phase" for household circuits, or "AC - Three phase" for three-phase power. The power factor field appears only for AC — it is not needed for DC.
Enter watts, amps, and power factor
Type the power in watts (zero or more) and the phase current in amps (must be above zero). For AC modes also enter the power factor, between 0 and 1 — use 1 for a purely resistive load.
Press Calculate, read volts
The result appears in volts (V), rounded to at most three decimals. Three phase shows both the line-to-line and the line-to-neutral voltage. Reset clears every field.
How watts become volts
- How do you convert watts to volts (DC)?
- The voltage V in volts (V) is equal to the power P in watts (W), divided by the current I in amps (A): V(V) = P(W) / I(A). For example, 100 W drawn at 2 A gives 100 / 2 = 50 V.
- How do you convert watts to volts for AC single phase?
- The RMS voltage V in volts (V) is equal to the power P in watts (W), divided by the power factor PF times the phase current I in amps (A): V(V) = P(W) / (PF × I(A)). A 3 kW single-phase load at 0.8 power factor and 15 A gives 3000 / (0.8 × 15) = 250 V.
- How does the three phase calculation differ?
- For a balanced three phase load the calculator shows two RMS voltages: line-to-line VL-L(V) = P(W) / (√3 × PF × I(A)) and line-to-neutral VL-N(V) = P(W) / (3 × PF × I(A)). For 3000 W at PF 0.8 and 10 A that is about 216.506 V line-to-line and 125 V line-to-neutral — the two differ by the factor √3, as they must.
- What is the power factor and why is it required for AC?
- The power factor is the ratio of real power (watts) to apparent power (volt-amps) in an AC circuit, always between 0 and 1. Resistive loads have PF ≈ 1; motors and electronics are typically 0.7–0.9. Below PF 1 more current flows for the same watts, so the voltage the same watts imply at the same amps is higher. DC has no phase shift, so this calculator takes no power factor for DC.
- Why does the calculator reject zero amps?
- Every formula here divides by the current, and division by zero is undefined — with zero current a wattage alone cannot tell you the voltage. Zero watts with a positive current is fine: it simply results in 0 V.
Privacy: every calculation runs in your browser tab — no value you type is sent anywhere. Results are ideal steady-state DC / balanced AC values; verify real installations with a multimeter.