Watts to Amps Calculator

Knowing how many watts a device uses is half the answer — the other half is how many amps it will draw, because breakers, cables and outlets are all rated in amps. Moving from power to current means dividing by voltage and, for motor or ballast loads, by the power factor.

Watts to Amps Calculator converts power to current for single-phase and three-phase supplies, reporting the current per phase alongside the total — the number you actually use for cable and breaker sizing.

Everything runs in the browser; nothing is uploaded.

• Single and three-phase: Select the system and the division adjusts automatically.
• Power factor input: 1 for resistive loads, 0.7-0.9 for motors.
• Per-phase current: The line current a breaker and cable must carry.
• Live formula: The division shown exactly as computed.
• Export: Copy or download as text, CSV or JSON.
• Learning guide: Power factor, phase and startup-surge notes.

1. Enter the power in watts (or pick kW / hp quick inputs).
2. Enter the voltage — line-to-neutral for 1P, line-to-line for 3P.
3. Set the power factor (1 for resistive, lower for motors).
4. Choose the phase system.
5. Read the current — per phase for three-phase.
6. Export the conversion if needed.

Example 1 — Oven. 3,000 W at 230 V, unit pf: 13.0 A.

Example 2 — Motor. 11 kW at 400 V three-phase, pf 0.86: about 18.5 A per phase.

Example 3 — Geyser. 3,000 W resistive on a 16 A circuit: 13 A, fits with headroom.

Example 4 — Circuit load. A 3.68 kW (16 A) single-phase circuit at unit pf draws 16 A at 230 V.

• Size the breaker right: Current is what breakers and cables carry.
• pf-aware: Motor loads get the honest amps, not the optimistic number.
• Three-phase ready: Per-phase current reported for balanced 3P loads.
• Explained maths: The division is shown step by step.
• Free and private: No uploads, no accounts, no logging.