OnlineTool.me

Watts to Amps Calculator

Enter circuit type, real power, voltage, and AC power factor to calculate current in amps.

Convert Watts to Amps

Enter circuit type, real power, voltage, and AC power factor to calculate current.

How to Use Watts to Amps Calculator

1

Select the Circuit Type

Choose DC, single-phase AC, or balanced three-phase AC.

2

Enter Power and Voltage

Use real watts and the operating voltage; for three-phase AC, use line-to-line voltage.

3

Add AC Power Factor

For AC loads, enter the operating power factor and compare the calculated amps with rated data.

Watts to Amps Calculator Features

  • DC, single-phase AC, and balanced three-phase AC modes
  • Live current calculation with AC power factor
  • Visible circuit assumptions and applied formula
  • Inline validation for zero voltage and invalid power factor

Common Use Cases

Check equipment operating current

Convert known real power and voltage into an approximate or exact formula-based current for the selected circuit model.

Compare AC power-factor scenarios

See how a lower power factor increases current for the same real power and voltage.

Limits and Important Notes

Result type: Exact calculation

Calculation Details

  • Select DC, single-phase AC, or balanced three-phase AC.
  • Enter real power in watts and operating voltage in volts.
  • For AC, enter power factor from greater than 0 through 1.
  • Divide real power by the voltage, power-factor, and phase terms that apply.

Formula

DC: I=P÷V; single-phase AC: I=P÷(V×PF); balanced three-phase AC: I=P÷(√3×Vline×PF)

Rounding

Current displays to two decimals at 1 A or more and three decimals below 1 A.

Default Assumptions

  • Watts mean real power rather than apparent power in volt-amperes.
  • Three-phase voltage is line-to-line and the load is balanced.
  • The entered power factor represents the operating condition.

Verified Example

Inputs: 1,200 W DC at 120 V.

Calculation: 1,200 ÷ 120 = 10.

Result: Current = 10 A.

Sources and Version

Version: Standard real-power relationships

Last verified: 2026-08-10

Update responsibility: OnlineTool.me

  • Use this for conversion and preliminary checking, then compare the result with equipment nameplate current and manufacturer documentation.
  • Do not use the result alone to size conductors, breakers, fuses, disconnects, generators, or other safety-critical electrical equipment.
  • Real systems may require efficiency, harmonics, starting current, duty cycle, imbalance, or local code requirements not modeled here.

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Frequently Asked Questions