Watts to Amps Calculator
Convert electrical power in watts to current in amps with this calculator. The correct formula depends on the voltage and, for AC circuits, may also depend on power factor. This makes it important to use the formula that matches the type of electrical system being considered.
Quick Answer
DC or resistive single-phase: Amps = Watts Γ· Volts
For a DC circuit or a purely resistive load, current equals power divided by voltage. For AC loads, power factor may be required: I = P Γ· (V Γ PF) for single-phase real power.
Watts, Volts, and Amps
Watts measure power, volts measure electrical potential difference, and amps measure current. The relationship between them depends on the circuit. For simple DC calculations, P = V Γ I. Rearranging gives I = P Γ· V.
AC Power and Power Factor
For a single-phase AC load where real power is known, current can be estimated using I = P Γ· (V Γ PF). Three-phase systems use a different relationship involving β3. If the load or installation is electrical work, use the equipment specifications and qualified guidance rather than relying on a simplified estimate.
Examples
100 W at 20 V = 5 A for DC.
1,000 W at 120 V = 8.33 A for a resistive load.
1,500 W at 230 V = 6.52 A for a resistive load.
2,000 W at 230 V with PF 0.9 = about 9.66 A single-phase.
Quick Reference
- Watts-to-amps is not a single fixed conversion because voltage matters.
- AC motors and other inductive loads can have power factors below 1.
- Use nameplate ratings when selecting wiring, breakers, or equipment.