20 amps to watts
At 120 volts, 20 amps delivers 2,400 watts; at 240 volts, 4,800 watts (power factor 1).
20 amps to watts at common voltages
| Voltage | Watts, W |
|---|---|
| 12 V DC | 240 |
| 24 V DC | 480 |
| 120 V | 2,400 |
| 240 V | 4,800 |
| 208 V three phase | 7,205 |
| 480 V three phase | 16,628 |
The AC and three-phase rows assume a power factor of 1, as for heaters and incandescent lamps. Motors and electronics draw more current for the same watts.
How to convert 20 amps to watts
Watts = amps × volts, so 20 amps carries 2,400 watts on a 120 V circuit and 4,800 watts on a 240 V circuit. On a 12 V DC system, 20 amps is 240 watts. At a power factor of 0.8, 20 amps at 120 V delivers 1,920 W.
How much of a 15 or 20 amp circuit 20 amps uses
On a 120 V circuit, a 20 amp load uses more than a 15 amp circuit can carry and 100% of a 20 amp circuit. A 20 amp load that runs for three hours or more should stay within 80% of the circuit rating: 12 A on a 15 amp circuit and 16 A on a 20 amp circuit. As a continuous load, 20 A needs at least a 25 amp breaker (125% of the current, rounded up to a standard size).
The wire a 20 amp circuit needs, in copper and aluminum, is on the 20 amp wire size page.
Nearby values
| Amps, A | 120 V, W | 240 V, W |
|---|---|---|
| 5 | 600 | 1,200 |
| 10 | 1,200 | 2,400 |
| 15 | 1,800 | 3,600 |
| 20 | 2,400 | 4,800 |
| 30 | 3,600 | 7,200 |
| 50 | 6,000 | 12,000 |
Appliances that draw about 20 amps
Amps to watts calculator
1 for heaters and lights; motors and electronics 0.8–0.95
- Current
- 20 A
- Voltage
- 120 V
- Kilowatts
- 2.4 kW
How it is calculated
- Watts = 20 × 120 = 2,400