How to convert amps to watts

How to convert electric current in amps (A) to electric power in watts (W).

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

DC amps to watts calculation formula

The power P in watts (W) is equal to the current I in amps (A), times the voltage V in volts (V):

P(W) = I(A) × V(V)

So watts are equal to amps times volts:

watt = amp × volt

or

W = A × V

Example

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

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

P = 3A × 110V = 330W

AC single phase amps to watts calculation formula

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

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 the 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 amps to watts calculation formula

Watts calculation with line to line voltage

The real power P in watts (W) is equal to square root of 3 times the power factor PF times the phase current I in amps (A), times the  line to line RMS voltage VL-L in volts (V):

P(W) = √3 × PF × I(A) × VL-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 = √3 × 0.8 × 3A × 110V = 457W

Watts calculation with line to neutral voltage

The calculation assumes the loads are balanced.

The real power P in watts (W) is equal to 3 times the power factor PF times the phase current I in amps (A), times the  line to neutral RMS voltage VL-0 in volts (V):

P(W) = 3 × PF × I(A) × VL-0(V)

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

watt = 3 × PF × amp × volt

or

W = 3 × PF × A × V

 

How to convert watts to amps ►

 

See also

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