Volts to Watts Calculator

Q: How do I convert volts to watts?

You also need the current in amps. DC: Watts = Volts × Amps. AC: Watts = Volts × Amps × Power Factor.

Q: How many watts is 12 volts at 10 amps?

For DC: 12V × 10A = 120W. This is a common calculation for 12V battery systems, car accessories, and solar setups.

Q: Can I convert volts to watts without knowing amps?

No. Volts alone cannot give you watts — you need current (amps) as well. Power = Voltage × Current (× Power Factor for AC).

Calculate power in watts from voltage and current for both DC and AC circuits. Useful for battery systems, solar panels, and electrical load calculations.

Calculate Watts from Volts

Voltage (V)

Current (Amps)

Circuit Type

Power Factor (AC only)

Result

—

Power (Watts)

—

Power (kW)

Formulas

DC Circuit:

Watts = Volts × Amps

AC Circuit:

Watts = Volts × Amps × Power Factor

Example Calculations

12V DC System (RV/Marine): 12V battery supplying 15A to a load.

Watts = 12 × 15 = 180W

48V Solar System: 48V bank with 20A output.

Watts = 48 × 20 = 960W

230V AC Single Phase: 10A load with PF = 0.9.

Watts = 230 × 10 × 0.9 = 2,070W

Practical Notes

For DC systems (solar, batteries, automotive), PF is always 1 — just multiply V × A.
For AC, you must include power factor unless you only need apparent power (VA).
Solar panel ratings are in watts at STC (Standard Test Conditions) — use this calc for real-world output at known V and A.
A car's 12V system supplying 10A delivers 120W — enough to run car lights, radios, and small inverters.
To find monthly kWh from this result, multiply watts × hours per day × 30 ÷ 1000.

Frequently Asked Questions

How do I convert volts to watts?

You need both voltage and current. DC: W = V × A. AC: W = V × A × PF. Volts alone can't tell you watts because power depends on how much current is flowing.

How many watts is 12 volts at 10 amps?

For a DC 12V system: 12 × 10 = 120W. This is typical for a car accessory socket drawing about 10A. A 100W laptop charger would draw about 8.3A from a 12V source.

Can I convert volts to watts without knowing amps?

No. You need current (amps) to calculate watts. If you only know voltage and resistance, use Ohm's law: Amps = Volts ÷ Resistance, then multiply by volts for watts.