Volts to Watts Conversion Calculator
Convert volts to watts by entering the voltage and current in amps, or the resistance of the circuit in the form below.
Convert Volts and Amps to Watts
Convert Volts and Ohms to Watts
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How to Convert Volts to Watts
Converting voltage, measured in volts, to power measured in watts is easy using the Watt’s Law power formula. Watt’s Law states that current is equal to power divided by voltage.
Multiplying both sides of this relationship by voltage, we can change this formula to also state that power is equal to voltage times current.
Volts to Watts Formula
This is the formula to convert volts to watts, using the current in amps:[1]
P(W) = V(V) × I(A)
Thus, the power P in watts it equal to the voltage V in volts times the current I in amps.
For example, let’s convert 12 volts to watts for a DC circuit with 2 amps of current.
P(W) = 12 V × 2 A
P(W) = 24 watts
So, 12 volts will consume 24 watts of power.
Conversion For AC Circuits
Converting voltage to wattage in AC electrical circuits uses the same formula with some slight modifications. This is because AC circuit power is comprised of a real power component, measured in watts (W), and a reactive power component, measured in volt-amps reactive (VAR).
Together, these components are called apparent power and are measured in volt-amps (VA). The real power component is the power that does the work, whereas reactive power is usually undesirable because it generates excess load on the transmission components. The ratio of real power to apparent power is called the power factor.
Formula for AC Circuits
To account for power factor when converting volts to watts, you can use the following formula:
P(W) = V(V) × I(A) × PF
Thus, in AC circuits, power P in watts is equal to the RMS voltage V times the current I in amps times the power factor.
For example, let’s convert 120 volts to watts for an AC electrical circuit with 15 amps of current and a power factor of .9.
P(W) = 120 V × 15 A × .9
P(W) = 1,620 watts
In this example, 120 volts will consume 1,620 watts of power.
Convert Volts to Watts using Resistance
It’s also possible to convert volts to watts for a simple resistive load if you know the resistance of the circuit. Use this formula to convert volts to watts using the resistance.
P(W) = V(V)2 ÷ R(Ω)
Thus, the power P in watts is equal to voltage V squared, divided by the resistance R in ohms.
For example, let’s convert 24 volts to watts for a DC circuit with 12 ohms of resistance.
P(W) = (24 V)2 ÷ 12 Ω
P(W) = 576 V ÷ 12 Ω
P(W) = 48 watts
The result is 48 watts.
Equivalent Volts and Watts Measurements
| Voltage | Power | Current |
|---|---|---|
| 1 volt | 1 watt | 1 amp |
| 1 volt | 2 watts | 2 amps |
| 1 volt | 3 watts | 3 amps |
| 1 volt | 4 watts | 4 amps |
| 2 volts | 2 watts | 1 amp |
| 2 volts | 4 watts | 2 amps |
| 2 volts | 6 watts | 3 amps |
| 2 volts | 8 watts | 4 amps |
| 3 volts | 3 watts | 1 amp |
| 3 volts | 6 watts | 2 amps |
| 3 volts | 9 watts | 3 amps |
| 3 volts | 12 watts | 4 amps |
| 4 volts | 4 watts | 1 amp |
| 4 volts | 8 watts | 2 amps |
| 4 volts | 12 watts | 3 amps |
| 4 volts | 16 watts | 4 amps |
| 5 volts | 5 watts | 1 amp |
| 5 volts | 10 watts | 2 amps |
| 5 volts | 15 watts | 3 amps |
| 5 volts | 20 watts | 4 amps |
| 6 volts | 6 watts | 1 amp |
| 6 volts | 12 watts | 2 amps |
| 6 volts | 18 watts | 3 amps |
| 6 volts | 24 watts | 4 amps |
| 7 volts | 7 watts | 1 amp |
| 7 volts | 14 watts | 2 amps |
| 7 volts | 21 watt | 3 amps |
| 7 volts | 28 watts | 4 amps |
| 8 volts | 8 watts | 1 amp |
| 8 volts | 16 watts | 2 amps |
| 8 volts | 24 watts | 3 amps |
| 8 volts | 32 watts | 4 amps |
| 9 volts | 9 watts | 1 amp |
| 9 volts | 18 watts | 2 amps |
| 9 volts | 27 watts | 3 amps |
| 9 volts | 36 watts | 4 amps |
| 10 volts | 10 watts | 1 amp |
| 10 volts | 20 watts | 2 amps |
| 10 volts | 30 watts | 3 amps |
| 10 volts | 40 watts | 4 amps |
| 11 volt | 11 watt | 1 amp |
| 11 volt | 22 watts | 2 amps |
| 11 volt | 33 watts | 3 amps |
| 11 volt | 44 watts | 4 amps |
| 12 volts | 12 watts | 1 amp |
| 12 volts | 24 watts | 2 amps |
| 12 volts | 36 watts | 3 amps |
| 12 volts | 48 watts | 4 amps |
| 24 volts | 24 watts | 1 amp |
| 24 volts | 48 watts | 2 amps |
| 24 volts | 72 watts | 3 amps |
| 24 volts | 96 watts | 4 amps |
| 48 volts | 48 watts | 1 amp |
| 48 volts | 96 watts | 2 amps |
| 48 volts | 144 watts | 3 amps |
| 48 volts | 192 watts | 4 amps |
| 120 volts | 120 watts | 1 amp |
| 120 volts | 240 watts | 2 amps |
| 120 volts | 360 watts | 3 amps |
| 120 volts | 480 watts | 4 amps |
| 240 volts | 240 watts | 1 amp |
| 240 volts | 480 watts | 2 amps |
| 240 volts | 720 watts | 3 amps |
| 240 volts | 960 watts | 4 amps |
Learn more Ohm’s Law electrical formulas and see more conversions on our Ohm’s Law calculator.
References
- Miller, C., Ugly’s Electrical References, 2020 Edition, 2020, Jones & Bartlett Learning, 16-23. https://books.google.com/books?id=1kS8DwAAQBAJ