# How to convert volts to watts

How to convert electrical voltage in volts (V) to electric power in watts (W).

You can calculate watts from volts and amps, but you can't convert volts to watts since watts and volts units do not measure the same quantity.

### DC volts to watts calculation formula

The power *P* in watts is equal to the voltage *V* in volts, times
the current *I* in amps:

*P*_{(W)} = * V*_{(V)}* *×* *
*I*_{(A)}

So watts are equal to volts times amps:

watt = volt × amp

or

W = V × A

#### Example

What is power consumption in watts when the current is 3A and the voltage supply is 15V?

Answer: the power P is equal to current of 3 amps times the voltage of 15 volts.

*P* = 15V × 3A = 45W

### AC single phase volts to watts calculation formula

The real power *P* in watts is equal to the
power factor *PF* times
the phase current *I* in amps, times the
RMS voltage *V* in volts:

*P*_{(W)} = * PF *×* I*_{(A)}* *×* V*_{(V)}

So watts are equal to power factor times amps times volts:

watt = * PF *×* *amp × volt

or

W = * PF *×* *A × V

#### Example

What is power consumption in watts when the power factor is 0.8 and the phase current is 3A and RMS voltage supply is 110V?

Answer: the power P is equal to power factor of 0.8 times current of 3 amps times voltage of 110 volts.

*P* = 0.8 × 3A × 110V = 264W

### AC three phase volts to watts calculation formula

The real power *P* in watts is equal to square root of 3 times the
power factor *PF* times the
phase current
*I* in amps, times the line to line RMS voltage *V*_{L-L} in volts:

*P*_{(W)} = *√*3
× * PF *×* I*_{(A)}* *×* V*_{L-L(V)}

So watts are equal to square root of 3 times power factor PF times amps times volts:

watt = *√*3
× * PF *×* *amp × volt

or

W = *√*3
× * PF *×* *A × V

#### Example

What is power consumption in watts when the power factor is 0.8 and the phase current is 3A and the RMS voltage supply is 110V?

Answer: the power P is equal to power factor of 0.8 times current of 3 amps times the voltage of 110 volts.

*P*_{(W)} = *√*3
× 0.8 × 3A × 110V = 457W

How to convert watts to volts ►