How the amps to watts calculator works
Electrical power depends on voltage and current. For direct current, the basic relationship is simple. For alternating current, real power can also depend on power factor, so this calculator lets you enter it.
Amps to watts formula
DC or resistive load: watts = volts × amps
AC real power: watts = volts × amps × power factor
Watts to amps: amps = watts ÷ (volts × power factor)
Scope and assumptions
This page uses a DC relationship or a single-phase AC real-power estimate. It does not calculate three-phase power, and it does not replace electrical design or safety checks. For AC circuits, use a known power factor and confirm whether the voltage is the relevant RMS voltage.
Example
A 120 V load drawing 10 A at a power factor of 1 uses 1,200 W.
If the same voltage and current had a power factor of 0.8, real power would be 960 W.
Whether you need to convert amps to watts for a DC load or are searching for an amps to watts calculator, the same voltage and current relationship applies. The reverse calculation is available too, so a watts to amps calculator result can be found from known power and voltage.
Amps to watts chart
Watts = amps × volts. This chart assumes DC or a power factor of 1 (resistive load). For AC loads with a lower power factor, multiply the result by the power factor.
| Amps | Watts at 12 V | Watts at 120 V | Watts at 240 V |
|---|---|---|---|
| 1 A | 12 | 120 | 240 |
| 5 A | 60 | 600 | 1,200 |
| 10 A | 120 | 1,200 | 2,400 |
| 15 A | 180 | 1,800 | 3,600 |
| 20 A | 240 | 2,400 | 4,800 |
| 30 A | 360 | 3,600 | 7,200 |
| 50 A | 600 | 6,000 | 12,000 |
Frequently asked questions
How many watts is one amp?
There is no single answer without voltage. At 120 V and power factor 1, one amp corresponds to 120 W.
Do I need power factor?
For DC, use 1. For AC loads, use the known power factor when you need real power rather than apparent power.
Can I convert watts back to amps?
Yes. Select Watts to amps, enter voltage and watts, and the calculator works backward using the same relationship.
How many watts is 10 amps?
Watts = amps × volts. 10 amps is 120 watts at 12 V, 1,200 watts at 120 V and 2,400 watts at 240 V, assuming a power factor of 1.
How do I convert amps to watts?
Multiply the current in amps by the voltage. For single-phase AC, also multiply by the power factor: watts = amps × volts × power factor.