Calculate voltage (V), current (I), resistance (R), or power (P) using Ohm's Law — enter any two values and all four quantities are calculated instantly.
V = I × R | P = V × I
| Voltage | V = I × R = P / I = √(P × R) |
| Current | I = V / R = P / V = √(P / R) |
| Resistance | R = V / I = V² / P = P / I² |
| Power | P = V × I = I² × R = V² / R |