Amps (A) to Watts (W) calculator and how to calculate

The SI unit of power *P* is Watts (W) while ampere (A) is the SI unit of electric current. To calculate power, in watts, you should multiply the voltage *V*, in volts (V) by the current *I* in amps (A).

*P*_{(W)} = *I*_{(A)} ×* V*_{(V)}

Therefore:

Watts (W) may be calculated by multiplying volts (V) by amps (A), as follows

Watt = amp × volt

Or

W = A × V

**Example
**

Given that the current through an electrical circuit is 4A and the voltage across the circuit is 110V, calculate its power consumption in watts.

*Solution*

Power *P* = Current *I* × Voltage *V*

P = 110V × 3A = 440W

The actual power *P* in watts (W) for AC single phase amps is calculated by multiplying the root mean square (RMS) of voltage by the power factor *PF* and then multiplying the result by the phase current *I*.

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

Therefore:

Watts = Volts × the Power factor × amps

watt = *PF *× amp × volt or W = *PF *× A × V

**Example
**

Calculate the Power Consumption in watts, given that the phase current is 4A, the RMS voltage is 110v and the power factor is 0.7.

*Solution*

Power *P *= power factor x the voltage in volts x current in amps

*P* = 0.7 × 4A × 110V = 308W

**Calculating watts using the line to line voltage**

The actual power *P* in this case, may be calculated by multiplying the phase current *I*, in amps (A), the power factor *PF* and the line to line RMS voltage *V _{L-L}*, which should be in Volts (V). You should then multiply the result with the square root of 3.

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

Therefore:

Watts = √3 × *PF* × Volts × Amps

**Example
**

Work out the power consumption in an electrical system, in watts, given that the phase current in the circuit is 3A, the RMS voltage is 110V and the power factor is 0.8.

*Solution*

Power *P* =*PF* × A × V × √3

*P* = *√*3 × 0.8 × 3A × 110V = 457W

**Using the line to neutral Voltage to calculate Watts**

To calculate power in watts using the line to neutral voltage, the assumption is that the loads in the circuit are balanced. In that case, you calculate the power *P* by multiplying the power factor *PF* times the line to neutral RMS V_{L-O} voltage, in Volts (V) and then multiplying the result by 3.

*P*_{(W)} = 3 × *PF *×* I*_{(A)} ×* V*_{L-0}_{(V)}

Therefore:

Watts is equivalent to 3 times the amps (A) multiplied by the power factor (*PF*) multiplied by the volts (V)

Watt = 3 × PF × amp × volt

or

W = 3 × PF × A × V