# Watts to Amps Calculator

> Watts to amps calculator: convert watts to amps for DC, single-phase AC, or three-phase AC circuits using voltage and power factor. Free, private, no signup.

- **Canonical URL:** https://boringtoolskit.com/watts-to-amps-calculator/
- **Category:** Energy & Electrical
- **Evidence level:** authored-methodology
- **Reviewed:** July 2026
- **Last verified:** 2026-10-12
- **Privacy:** Inputs and results stay in this browser unless the page clearly labels an external request.

## How it works

DC: I = P ÷ V. Single-phase AC: I = P ÷ (V × PF). Three-phase AC: I = P ÷ (√3 × V × PF).

## Assumptions

- Entered watts represent real power.
- Three-phase voltage is treated as line-to-line voltage.
- Efficiency, starting current, harmonics, and code sizing factors are excluded.

## Common questions

### How do you convert watts to amps?

Divide power in watts by voltage. For direct current, amps = watts ÷ volts. For single-phase AC, amps = watts ÷ (volts × power factor). For three-phase AC, amps = watts ÷ (√3 × volts × power factor).

### How many amps is 1,500 watts at 120 volts?

At 120 V single-phase AC with a typical power factor, 1,500 watts draws about 12.5 amps. The exact figure depends on the power factor and whether the circuit is DC, single-phase AC, or three-phase AC.

### What is power factor and why does it matter?

Power factor is the ratio of real power to apparent power in an AC circuit, usually between 0 and 1. Because only real power (watts) does useful work, an AC load draws more current at a lower power factor. This calculator includes a power-factor input for AC conversions.

### Can I use this estimate to size wiring or breakers?

No. The result is a planning estimate and excludes efficiency, starting current, harmonics, and electrical-code sizing factors. Always consult a qualified electrician and local electrical code before sizing conductors, breakers, or equipment.

## Related tools

- /electricity-cost-calculator/
- /battery-runtime-calculator/
- /unit-conv/

## Sources

- [SI units: ampere, volt, watt](https://www.nist.gov/pml/owm/metric-si/si-units)
- [Electrical safety](https://www.osha.gov/electrical)

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*Local planning estimate. Verify current terms, rates, and policies before acting.*