Watts to Amps Calculator

Q: How do I convert watts to amps?

For DC: Amps = Watts ÷ Volts. For single phase AC: Amps = Watts ÷ (Volts × PF). For three phase AC: Amps = Watts ÷ (√3 × Volts × PF).

Q: How many amps is 1000 watts at 120V?

At 120V with PF=1 (resistive load): 1000 ÷ 120 = 8.33 amps. At PF=0.9: 1000 ÷ (120×0.9) = 9.26 amps.

Q: Does power factor affect the watts to amps calculation?

Yes, for AC circuits. Power factor (PF) accounts for reactive power in inductive or capacitive loads. Resistive loads like heaters have PF=1. Motors typically have PF of 0.7–0.9.

Convert watts to amperes for DC circuits, single phase AC, and three phase AC systems. Includes power factor for accurate AC results.

This calculator provides estimates only. Always consult a qualified electrician for real installations.

Convert Watts to Amps

Power (Watts)

Voltage (V)

Circuit Type

Power Factor (AC only)

Result

—

Current (Amps)

Formulas

DC Circuit:

Amps = Watts ÷ Volts

Single Phase AC:

Amps = Watts ÷ (Volts × Power Factor)

Three Phase AC:

Amps = Watts ÷ (√3 × Volts × Power Factor)

Where √3 ≈ 1.732. Power factor (PF) is 1.0 for pure resistive loads and typically 0.7–0.95 for motors and mixed loads.

Example Calculations

DC Example: A 500W solar panel connected to a 48V battery bank.

Amps = 500 ÷ 48 = 10.42 A

Single Phase AC Example: A 2,000W motor at 230V with PF = 0.85.

Amps = 2000 ÷ (230 × 0.85) = 2000 ÷ 195.5 = 10.23 A

Three Phase AC Example: A 10 kW (10,000W) motor at 415V with PF = 0.9.

Amps = 10,000 ÷ (1.732 × 415 × 0.9) = 10,000 ÷ 646.5 = 15.47 A

Practical Notes

Use PF = 1.0 for resistive loads: heaters, incandescent bulbs, toasters.
Use PF = 0.8–0.95 for induction motors, compressors, and mixed commercial loads.
LED drivers and switching power supplies often have PF of 0.9–0.99.
Three phase draws about 42% less current per phase than single phase for the same power.
Always size wire and breakers to the calculated amps, not just the watt rating of the device.

Frequently Asked Questions

How do I convert watts to amps?

DC: Amps = W ÷ V. Single phase AC: Amps = W ÷ (V × PF). Three phase: Amps = W ÷ (1.732 × V × PF). Always know your voltage and power factor before calculating for AC circuits.

How many amps is 1000 watts at 120V?

At PF=1 (resistive load): 1000 ÷ 120 = 8.33A. At PF=0.9 (typical inductive): 1000 ÷ (120 × 0.9) = 9.26A. Always check if the load is resistive or inductive.

Does power factor affect the watts to amps calculation?

Yes, for AC circuits. A lower power factor means more current is drawn for the same real power. This is why a 1kW motor pulls more amps than a 1kW heater — the motor has a lower PF. For DC circuits, PF is always 1.