Convert watts, kilowatts, or megawatts to amps for DC, single-phase AC, or balanced three-phase AC with power factor.
Calculator
Watts to Amps Results
Review the converted result, power components, formula inputs, and common-voltage comparisons.
Power and Current Components
Calculation Details
| Metric | Value | Note |
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Current at Common Voltages
Uses the entered real power or current and AC power factor. Each row changes the system and voltage.
| System | Voltage | Result | Power factor |
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Convert watts or kilowatts to amps
Enter real electrical input power in watts, kilowatts, or megawatts, then select DC, single-phase AC, or balanced three-phase AC. The calculator converts the power to watts, applies the selected voltage relationship and power factor, and reports current in amps and milliamps.
DC: A = W / V
single phase: A = W / (V x PF)
three phase, line-to-line: A = W / (√3 x VLL x PF)
three phase, line-to-neutral: A = W / (3 x VLN x PF)
Watts-to-amps examples
A 1,500 W resistive load at 120 V draws 12.5 A. At power factor 0.8, the same 1,500 W real load requires 15.625 A and 1,875 VA of apparent power. A balanced 15 kW three-phase load at 480 V line-to-line and 0.9 power factor draws about 20.05 A.
Line-to-line versus line-to-neutral voltage
Balanced three-phase power can be written with either line-to-line voltage or line-to-neutral voltage. Choose the relationship that matches the voltage you entered. For the same wye system, line-to-line voltage is √3 times line-to-neutral voltage, so the two formulas produce the same line current when their corresponding voltages are used.
For example, a 120/208 V wye system has about 120 V line-to-neutral and 208 V line-to-line. Enter 208 V with the line-to-line option or 120 V with the line-to-neutral option. Do not mix the voltage value and formula type.
Power factor, VA, and VAR
Watts measure real power. Volt-amperes measure apparent power carried by the source and conductors. For the simplified sinusoidal model used here, power factor equals watts divided by VA, and reactive volt-amperes are calculated from the power triangle. DC fixes power factor at 1 and reactive power at zero.
The US Department of Energy's industrial electrification framework uses the √3 x voltage x current x power-factor relationship for typical balanced three-phase loads.
Reference conversions at common voltages
The result table recalculates the entered real power at common DC, US single-phase, and three-phase voltages. AC rows use the entered power factor. The table is a comparison aid; it does not mean the same equipment can operate at every listed voltage.
Continuous-load planning
Choose continuous-load planning to display 125% of calculated current. This is only a planning value, not a breaker or conductor recommendation. Use the electrical load calculator to enter continuous and noncontinuous loads separately, then verify equipment and code requirements.
Frequently asked questions
Is 1,500 watts always 12.5 amps?
No. It is 12.5 A only at 120 V with power factor 1 in DC or single-phase AC. Current changes with voltage, system type, and power factor.
Can I enter kilowatts?
Yes. Select kW and enter the kilowatt value directly; the calculator multiplies it by 1,000 before solving current.
Should I use input or output watts?
Use electrical input real power. Mechanical motor output, cooling capacity, and power-supply output may not equal electrical input power.
Does this choose a breaker or wire?
No. Use the calculated current as one input to a complete design. See the breaker size calculator and wire size calculator for transparent preliminary checks.
How do I reverse the conversion?
Use the amps to watts calculator with the same voltage, system type, and power factor.