What Is a Watts to Amps Calculator?
A watts to amps calculator converts electrical power (in watts) into current (in amps) using the circuit voltage. Because power, voltage, and current are linked, you need the voltage to make the conversion. This tool is handy for sizing wires, breakers, and power supplies, and for understanding appliance ratings. Enter the power and voltage, and the calculator returns the current in amps.
How to Use the Calculator
- Enter the power in watts.
- Enter the voltage.
- For AC, enter the power factor if known.
- Calculate — see the current in amps.
The Watts to Amps Formula
For a DC circuit (and resistive AC):
Amps = Watts ÷ Volts
For example, 1,200 watts at 120 volts draws 1,200 ÷ 120 = 10 amps. For AC circuits with a power factor, the formula becomes Amps = Watts ÷ (Volts × Power Factor).
Common Conversions at 120 V
| Watts | Amps (at 120 V) |
|---|---|
| 600 W | 5 A |
| 1,200 W | 10 A |
| 1,800 W | 15 A |
| 2,400 W | 20 A |
Why Voltage Matters
The same power draws different current at different voltages. At 240 V, a 1,200 W device draws only 5 amps instead of 10 amps at 120 V. This is why higher-voltage systems can deliver the same power with thinner wires and lower current.
Practical Uses
- Circuit sizing: ensure devices don't exceed breaker ratings.
- Wire gauge: current determines safe wire thickness.
- Generators and inverters: match output to load.
Note: For electrical work, follow local codes and consult a licensed electrician.
Frequently Asked Questions
How do you convert watts to amps?
Divide the power in watts by the voltage: Amps = Watts ÷ Volts. For AC circuits, also divide by the power factor.
How many amps is 1,500 watts?
At 120 volts, 1,500 watts is 1,500 ÷ 120 = 12.5 amps. At 240 volts, it is 6.25 amps.
Why do I need the voltage to convert?
Power equals voltage times current, so without voltage you cannot separate current from power. The same wattage draws different current at different voltages.
What is power factor in AC circuits?
Power factor accounts for the phase difference between voltage and current in AC. It reduces the effective power, so current = watts ÷ (volts × power factor).
Is this watts to amps calculator free?
Yes — it is completely free, requires no signup, and converts for DC and AC circuits.