Watts to Amps Calculator
Convert watts to amps — or amps to watts — for DC, AC single-phase, and AC three-phase circuits, with power factor handled properly. The conversion the back of every appliance label assumes you know.
Reviewed by MyEnergyToolkit Editorial Team · Updated July 24, 2026 · Methodology & sources
1.0 resistive · 0.8–0.95 motors.
Current draw
0 A
A = W ÷ (V × PF)
Estimates for planning only. Always verify against your local electrical code and consult a licensed electrician before sizing circuits.
How to convert watts to amps
Three formulas, picked automatically by current type: DC: A = W ÷ V. AC single-phase: A = W ÷ (V × PF). AC three-phase: A = W ÷ (1.732 × V × PF), where 1.732 is √3. Going the other way (amps to watts) just inverts them. The power factor matters for motors and compressors — at PF 0.8, the same watts pull 25% more amps than a resistive load, and your wiring must carry the amps.
The "breaker fit" chip applies the common 80% continuous-load rule to standard breaker sizes, a quick sanity check — not a substitute for code compliance.
Watts-to-amps conversion chart
These quick-reference values assume DC or a resistive single-phase AC load with a power factor of 1. Motors and other inductive AC loads usually draw more current.
| Power | 12 V | 24 V | 48 V | 120 V | 240 V |
|---|---|---|---|---|---|
| 100 W | 8.33 A | 4.17 A | 2.08 A | 0.83 A | 0.42 A |
| 500 W | 41.67 A | 20.83 A | 10.42 A | 4.17 A | 2.08 A |
| 1,000 W | 83.33 A | 41.67 A | 20.83 A | 8.33 A | 4.17 A |
| 1,500 W | 125 A | 62.5 A | 31.25 A | 12.5 A | 6.25 A |
| 3,000 W | 250 A | 125 A | 62.5 A | 25 A | 12.5 A |
How many amps is 1,000 watts?
At 120 V, 1,000 watts is 8.33 amps. At 240 V it is 4.17 amps; at 24 V DC it is 41.67 amps; and at 12 V DC it is 83.33 amps. Voltage must always be included because watts alone cannot determine current.
Watts to amps for three-phase power
For a balanced three-phase system using line-to-line voltage, use A = W ÷ (1.732 × V × PF). For example, a 10,000 W load at 400 V and 0.9 power factor draws about 16.0 A. Use the equipment nameplate power factor whenever it is available.
Watts to amps FAQ
How do I convert watts to amps?
DC or resistive AC: amps = watts ÷ volts (1,200 W on 120 V = 10 A). AC with power factor: amps = watts ÷ (volts × PF). Three-phase: amps = watts ÷ (1.732 × volts × PF).
What is power factor and when do I need it?
The ratio of real to apparent power in AC circuits. Resistive loads (heaters, kettles) are ~1.0; motors and compressors run 0.7–0.95. Lower PF means more amps for the same watts.
How many amps is 1500 watts?
12.5 A on 120 V — why a space heater nearly fills a 15 A circuit — or about 6.5 A on 230 V. Continuous loads should stay at or below 80% of the breaker rating.
Why does three-phase use a 1.732 factor?
1.732 is √3. In a balanced three-phase system, power = √3 × line voltage × line current × PF, so current = watts ÷ (√3 × volts × PF).