Ohm's Law Calculator (V = IR)
Ohm's Law defines the fundamental relationship between voltage, current, and resistance in an electrical circuit: V = IR. Named after German physicist Georg Simon Ohm, this law is the cornerstone of circuit analysis and electrical engineering. This calculator lets you solve for any one of the three variables and also computes the power dissipated.
Ohm's Law states that the voltage (V) across a conductor is directly proportional to the current (I) flowing through it, with the constant of proportionality being the resistance (R):
- V = I × R — Voltage equals current times resistance
- I = V / R — Current equals voltage divided by resistance
- R = V / I — Resistance equals voltage divided by current
The calculator also computes electrical power using P = IV, which tells you how much energy the circuit dissipates per second (measured in Watts).
Units: Voltage is in Volts (V), current in Amperes (A), resistance in Ohms (Ω), and power in Watts (W). Ohm's Law applies to ohmic (linear) materials where resistance remains constant regardless of applied voltage.