Introduction
This Watts to Amps Calculator helps you quickly convert electric power in watts to current in amps. This tool handles the calculation for DC, AC single phase, and AC three phase circuits. All you need to enter is the power in watts and the voltage in volts. For AC circuits, you can also set the power factor and choose between line-to-line or line-to-neutral voltage.
The basic formula is simple: Amps = Watts ÷ Volts. For AC circuits, the formula also includes the power factor and, for three phase systems, a √3 multiplier. This calculator handles all of these cases so you do not have to worry about picking the right equation. If you need to go the other direction, our Amps to Watts Calculator can help with that conversion.
Electricians, students, engineers, and homeowners can all use this tool to size wires, check circuit breakers, or plan electrical loads. Just pick your current type, enter your values, and hit Calculate to get your result instantly.
How to Use Our Watts to Amps Calculator
Enter your power and voltage values below, and this calculator will instantly convert watts to amps. It works for DC, AC single phase, and AC three phase circuits.
Current Type: Pick the type of current your circuit uses. Choose DC for batteries, AC Single Phase for home outlets, or AC Three Phase for industrial power systems.
Power: Type in the power value of your device. Use the dropdown to select milliwatts (mW), watts (W), or kilowatts (kW). You can find this number on your device's label or manual.
Voltage: Enter the voltage of your power source. Use the dropdown to pick millivolts (mV), volts (V), or kilovolts (kV). You can also use the preset dropdown to quickly select a common voltage like 120V or 240V.
Power Factor: This field shows up only for AC circuits. Enter a value between 0.01 and 1.0. Most home appliances have a power factor between 0.8 and 1.0. If you are not sure, leave it at 1.
Voltage Type: This field shows up only for AC three phase circuits. Choose Line to Line (L-L) if you measure voltage between two hot wires. Choose Line to Neutral (L-N) if you measure voltage between a hot wire and neutral.
Calculate: Press the Calculate button to see your result in amps and milliamps. The tool also shows the full math so you can check the work. Press Reset to clear all fields and start over.
How to Convert Watts to Amps
Watts and amps are two ways to measure electricity. Watts measure how much power a device uses. Amps measure how much electric current flows through a wire. To find amps from watts, you need to know the voltage, which is the force that pushes electricity through a circuit. For a deeper understanding of the relationship between voltage, current, and resistance, see our Ohms Law Calculator.
Watts to Amps Formula
The basic formula is simple: Amps = Watts ÷ Volts. For example, a 1,000-watt device on a 120-volt circuit draws about 8.33 amps. This formula works directly for DC (direct current), which is the type of power batteries use.
AC Single Phase
For AC single phase power, which is what most homes use, you also need the power factor. The power factor is a number between 0 and 1 that shows how efficiently a device uses electricity. The formula becomes: Amps = Watts ÷ (Volts × Power Factor). Most home appliances have a power factor between 0.8 and 1.0.
AC Three Phase
Factories and large buildings often use AC three phase power. For three phase circuits with line-to-line voltage, the formula is: Amps = Watts ÷ (√3 × Volts × Power Factor). If you measure line-to-neutral voltage instead, you replace √3 with 3.
Why This Matters
Knowing the amps a device draws helps you pick the right wire size, choose the correct circuit breaker, and avoid overloading your electrical system. Overloaded circuits can trip breakers or cause fires. Electricians, engineers, and homeowners all use this conversion to keep electrical systems safe and working properly.