# Free Online calculation of electrical power and energy : formula and calculator

## AC POWER calculator for single phase or 3-phase system (balanced load)

### Active and apparent electrical power :

V

A

appliance

VA

W

### Energy calculation :

If you want to calculate energy associated to this active power, fill the time value below (number of hours and days the appliance is running) :

One year (365 days)

Currency :

Cost of energy : €/kWh

Total amount of electricity bill : €

### Formula to calculate power, current and voltage in single phase wiring :

P=U*I*cosφ

I=P/(U*cosφ)

U=P/(I*cosφ)

P = power in watt (W)

U = voltage in Volt (V)

I = current in ampere (A)

cos φ = cosinus phi (without unit)

### Formula to calculate power, current and voltage in three-phase wiring (balanced load, equal loads on each of three phases) :

P=√3*U*I*cosφ

I=P/(√3*U*cosφ)

U=P/(√3*I*cosφ)

P = power in watt (W)

U = voltage in Volt (V)

I = current in ampere (A)

cos φ = cosinus phi (without unit)

### Formula to calculate power, current and voltage in three-phase wiring (unbalanced load, different loads on each of three phases) :

Pt=P1+P2+P3

P1=V*I1*cosφ1

I1=P1/(V*cosφ1)

Same thing for each phase…

V=P1/(I*cosφ1)

Pt = total power of the circuit in watt (W)

P1, P2, P3 = power of phase 1, phase 2 and phase 3 in watt (W)

V = voltage in Volt (V) exemple : V1=230 V in 400 V three-phases circuit

I1, I2, I3 = current of phase 1, phase 2 and phase 3 in ampere (A)

Cos φ1, Cos φ2 , Cos φ3 = cosinus phi of each phase (without unit)