Volts to Watts Calculator
Convert volts to watts for any current. Enter the voltage in volts and current in amps to calculate power in watts. Works for 120V, 240V, and three-phase systems.
How to Convert Volts to Watts
The formula to convert volts to watts is: Watts = Volts × Amps. This comes directly from Ohm's Lawand the power equation P = V × I, where P is power in watts, V is voltage in volts, and I is current in amperes.
Single-phase: W = V × A
Three-phase: W = V × A × √3 (1.732)
For example, a 120-volt circuit drawing 15 amps delivers 1,800 watts (120 × 15). The same 15 amps at 240 volts delivers 3,600 watts — which is why high-power appliances like dryers and ovens use 240V circuits to deliver more power without increasing current.
If you know the resistance instead of the current, you can also use: Watts = Volts² ÷ Ohms. This alternative formula is useful when you know the voltage across a resistor and its resistance value.
Volts to Watts Conversion Chart
| Voltage | @ 1A | @ 5A | @ 10A | @ 15A | @ 20A |
|---|---|---|---|---|---|
| 5 V | 5 W | 25 W | 50 W | 75 W | 100 W |
| 12 V | 12 W | 60 W | 120 W | 180 W | 240 W |
| 24 V | 24 W | 120 W | 240 W | 360 W | 480 W |
| 120 V | 120 W | 600 W | 1,200 W | 1,800 W | 2,400 W |
| 240 V | 240 W | 1,200 W | 2,400 W | 3,600 W | 4,800 W |
| 480 V | 480 W | 2,400 W | 4,800 W | 7,200 W | 9,600 W |
Frequently Asked Questions
How to convert volts to watts?
Multiply volts by amps to get watts. The formula is: Watts = Volts × Amps. For example, 120 volts at 10 amps equals 1,200 watts (120 × 10 = 1,200). For three-phase circuits, multiply by √3 (1.732): Watts = Volts × Amps × 1.732.
How many watts is 120 volts?
It depends on the current (amps). At 120 volts and 1 amp, you get 120 watts. At 120 volts and 15 amps, you get 1,800 watts. At 120 volts and 20 amps, you get 2,400 watts. You always need to know the amperage to convert volts to watts.
How many watts is 240 volts at 30 amps?
240 volts at 30 amps equals 7,200 watts (240 × 30 = 7,200). This is the capacity of a typical 30-amp dryer or EV charger circuit running on a 240V supply.
What is the difference between volts and watts?
Volts measure electrical pressure (how hard electricity is pushed through a circuit). Watts measure power (the rate of energy use or work done). Think of it like water: voltage is the water pressure, current (amps) is the flow rate, and watts are the total work being done. You need both volts and amps to calculate watts.
Can you convert volts to watts without amps?
No, you cannot convert volts to watts without knowing the current (amps) or the resistance (ohms). Watts = Volts × Amps. If you know the resistance instead of amps, you can use Watts = Volts² ÷ Ohms. Without either amps or resistance, the conversion is impossible.
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