Electrical Power (P = V²/R)

P = \frac{V^{2}}{R}

P =

V =

R =

Enter your known values, leave one input blank, and solves for the missing one. Try different units for next level excitement!

Learning zone

With the supply voltage fixed — as it is at every wall outlet — power dissipated varies inversely with resistance: halve the resistance and the power doubles. A 1000 W heating element on 230 V mains must therefore be built with about 53 Ω of resistance. Solving for V takes the principal positive square root, the voltage's magnitude.

Electrical Power (P = V²/R)

P = \frac{V^{2}}{R}

Where

$P$ = Power
$V$ = Voltage
$R$ = Resistance

Missing one of these? Work it out first, then come back

Power — Electrical Power (P = VI), Electrical Power (P = I²R)
Voltage — Ohm's Law, Electrical Power (P = VI)
Resistance — Ohm's Law, Electrical Power (P = I²R)

Part of this formula set

The Ohm's law wheel

4 formulasOhm's law and the three power equations, arranged so that each one omits exactly one of voltage, current, resistance and power.