wattsElectrical power, made clear
Watts to amps calculator
Choose your circuit, enter the voltage, and see exactly how power becomes current.
01 Set up your calculation
Calculated current
1,500 W at 120 V · single phase · PF 1
- Equivalent current
- 12,500 mA
- Apparent power
- 1,500 VA
A power conversion, not a wire or breaker sizing recommendation. Three-phase results assume a balanced load.
Compare voltages
Same power and circuit. Different voltage.
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One value per line, or separate with commas. Do not use thousands separators. Uses the circuit and units above.
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Use the right nameplate value. A motor’s output rating does not include its losses. AC watts also cannot be converted to amps without voltage and power factor. This calculator keeps those assumptions visible.
Behind the calculation
How to convert watts to amps
Watts measure electrical power. Amps measure electric current. A watt does not correspond to a fixed number of amps: voltage and the circuit’s characteristics determine the relationship. Start with the electrical input power, select DC or the correct AC circuit, then enter the voltage. For AC real power, also supply the power factor. The result updates as you type, with the exact relationship shown beside your inputs.
I = P / VI = P / (V × PF)I = P / (√3 × VLL × PF)I = P / (3 × VLN × PF)In these equations, I is current in amperes, P is real electrical power in watts, V is voltage, and PF is power factor. AC voltage and current are RMS values. Three-phase power means total power across the three phases; the calculated current is the current in a line conductor, not three line currents added together. Reverse the direction to multiply current by the same factors and find power.
From the formula to a useful answer
1,500 watts at 120 volts
With a single-phase supply and power factor of 1, 1,500 ÷ (120 × 1) gives 12.5 amps. At the same voltage and a power factor of 0.8, the current is 15.625 amps. The watts have stayed the same; the required current has changed. That is why a wattage alone is not enough information.
15 kW on balanced three-phase AC
For total input power of 15,000 W, 480 V measured line to line, and a power factor of 0.9, the line current is about 20.047 A. If your known voltage is line to neutral, switch the reference before calculating. Do not enter 277 V as line-to-line voltage for a nominal 480/277 V system. The calculator shows the selected reference with the answer so a copied result retains its context.
The comparison table holds your inputs constant while changing voltage. In reverse mode it holds current constant and compares power instead. This is a mathematical comparison, not permission to connect a particular appliance to a different supply. Equipment voltage ratings still apply.
Real power, apparent power and PF
Real power is measured in W or kW. Apparent power is measured in VA or kVA. Power factor is the ratio of real to apparent power, as explained in Fluke’s power factor guide. For an AC load, dividing watts by voltage alone assumes a power factor of 1. That assumption may be unsuitable for motors, power supplies and other equipment.
If your equipment label specifies VA, choose apparent power. The current formula then uses voltage and the phase multiplier without another PF term. Entering a VA rating as though it were watts and then applying a power factor would mix two different quantities. Apparent power mode therefore hides the PF input.
Power factor is also different from a motor’s efficiency. A motor labeled with shaft output power needs an appropriate efficiency adjustment before its electrical input power is known. This tool does not silently estimate efficiency, starting current, duty cycle, or cable losses.
Common questions
How many amps are 1,000 watts?
At 120 V DC, or 120 V single-phase AC with PF 1, 1,000 W is about 8.333 A. At 240 V under the same assumptions it is about 4.167 A. Select your actual circuit and voltage for a meaningful answer.
Can I enter kilowatts or milliamps?
Yes. The input and result selectors support W and kW, or VA and kVA in apparent power mode, plus A and mA. One kilowatt is 1,000 watts and one ampere is 1,000 milliamperes. Conversions use full internal precision; the decimal selector controls display rounding.
Does this calculate a breaker rating or wire size?
No. The result is calculated electrical current. Breaker and conductor selection depend on installation conditions, equipment requirements and applicable electrical rules that these inputs do not describe.
Can it handle unbalanced three-phase loads?
The three-phase modes assume a balanced system. For unbalanced loads, phase-by-phase information and an appropriate measurement or analysis method are needed. One total power and one voltage cannot describe every individual line current.
A capable tool, free from the first calculation
Watts to Amps exists to make this one conversion useful in real work: clear assumptions, readable formulas, reversible units, convenient comparisons and an exportable batch table. The complete calculator is free, including CSV export. There is no account, paywall or tracking script.
Calculations run in your browser. Inputs are not submitted to an application server. Settings are saved in this browser only if you select “Remember these settings”; unchecking it removes that saved record. Reset also clears the saved settings. CSV and print actions create a copy for you to keep. The hosting provider still handles normal web requests to deliver the site. Decimal output is a calculation, not a guarantee that a nameplate value or measurement is that precise.