Watts to amps conversion table
Amps = watts ÷ volts. The table assumes DC or a resistive AC load (power factor 1.0). Motors and compressors draw more current for the same watts, so divide the answer by the power factor, usually 0.8 to 0.9, or use the calculator with power factor.
| Watts | 12 V | 24 V | 120 V | 240 V |
|---|---|---|---|---|
| 10 | 0.83 | 0.42 | 0.08 | 0.04 |
| 25 | 2.08 | 1.04 | 0.21 | 0.1 |
| 40 | 3.33 | 1.67 | 0.33 | 0.17 |
| 50 | 4.17 | 2.08 | 0.42 | 0.21 |
| 60 | 5 | 2.5 | 0.5 | 0.25 |
| 75 | 6.25 | 3.12 | 0.62 | 0.31 |
| 100 | 8.33 | 4.17 | 0.83 | 0.42 |
| 150 | 12.5 | 6.25 | 1.25 | 0.62 |
| 200 | 16.7 | 8.33 | 1.67 | 0.83 |
| 250 | 20.8 | 10.4 | 2.08 | 1.04 |
| 300 | 25 | 12.5 | 2.5 | 1.25 |
| 400 | 33.3 | 16.7 | 3.33 | 1.67 |
| 500 | 41.7 | 20.8 | 4.17 | 2.08 |
| 600 | 50 | 25 | 5 | 2.5 |
| 750 | 62.5 | 31.2 | 6.25 | 3.12 |
| 800 | 66.7 | 33.3 | 6.67 | 3.33 |
| 1,000 | 83.3 | 41.7 | 8.33 | 4.17 |
| 1,200 | 100 | 50 | 10 | 5 |
| 1,500 | 125 | 62.5 | 12.5 | 6.25 |
| 1,800 | 150 | 75 | 15 | 7.5 |
| 2,000 | 167 | 83.3 | 16.7 | 8.33 |
| 2,400 | 200 | 100 | 20 | 10 |
| 3,000 | 250 | 125 | 25 | 12.5 |
| 3,500 | 292 | 146 | 29.2 | 14.6 |
| 4,000 | 333 | 167 | 33.3 | 16.7 |
| 4,500 | 375 | 188 | 37.5 | 18.8 |
| 5,000 | 417 | 208 | 41.7 | 20.8 |
| 6,000 | 500 | 250 | 50 | 25 |
| 7,500 | 625 | 312 | 62.5 | 31.2 |
| 10,000 | 833 | 417 | 83.3 | 41.7 |
How to use the chart
- Find the wattage on the nameplate or the label of the appliance.
- Pick the voltage it runs on: 120 V for ordinary outlets, 240 V for dryers, ranges and large AC, 12 V or 24 V for cars, RVs, boats and solar systems.
- Read the amps. If the wattage is between two rows, add the rows: 1,200 W plus 300 W is 1,500 W.
Then check the circuit. A 15 A breaker should carry no more than 12 A of continuous load, which is 1,440 W at 120 V, and a 20 A breaker no more than 16 A, or 1,920 W. Continuous means three hours or more under the 80% rule.
Common appliances in amps
| Appliance | Watts | Amps at 120 V |
|---|---|---|
| Space heater | 1,500 | 12.5 |
| Microwave | 1,100 | 9.2 |
| Hair dryer | 1,800 | 15 |
| Toaster | 1,200 | 10 |
| Coffee maker | 1,000 | 8.3 |
| Refrigerator (running) | 150 | 1.3 |
| Window AC, 8,000 BTU | 700 | 5.8 |
| Laptop charger | 65 | 0.5 |
Sizing a wire for that current? The wire size calculator checks both ampacity and voltage drop, and the step-by-step guide covers single phase, three phase and power factor.
Frequently asked questions
How many amps is 100 watts?
8.33 amps at 12 V, 4.17 at 24 V, 0.83 at 120 V and 0.42 at 240 V.
How many amps is 1,000 watts?
8.33 amps at 120 V and 4.17 amps at 240 V.
How many watts is a 15 amp circuit?
1,800 W at 120 V in total, or 1,440 W for a continuous load.
Why do 12 V loads draw so much current?
Because power equals volts times amps, a lower voltage needs more amps for the same watts. That is why 12 V wiring needs thick wire.