Ohm's Law Calculator
Calculate voltage, current, resistance, or power instantly. Enter any two known values and solve for the remaining parameters.
Enter Any Two Known Values
Leave two fields blank or set them to solve.
Formula Breakdown
Ohm's LawEnter any two parameters on the left to view corresponding formulas and computed results.
Volts (V)
Amperes (A)
Ohms (Ω)
Watts (W)
About Ohm's Law & Electrical Formulas
Understand the fundamental relationship between voltage, current, resistance, and power.
Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points. Introducing electrical resistance yields the classic equation $V = I \times R$, where voltage ($V$) equals current ($I$) multiplied by resistance ($R$).
By combining Ohm's Law with Joule's Law of electrical power ($P = V \times I$), engineers can calculate any missing electrical parameter as long as two variables are known.
Voltage Calculation ($V$)
Computed as $V = I \times R$, $V = \frac{P}{I}$, or $V = \sqrt{P \times R}$.
Current Calculation ($I$)
Computed as $I = \frac{V}{R}$, $I = \frac{P}{V}$, or $I = \sqrt{\frac{P}{R}}$.
Resistance Calculation ($R$)
Computed as $R = \frac{V}{I}$, $R = \frac{V^2}{P}$, or $R = \frac{P}{I^2}$.
Power Calculation ($P$)
Computed as $P = V \times I$, $P = I^2 \times R$, or $P = \frac{V^2}{R}$.
Any Two Known Values
Input any valid combination of two parameters to automatically solve for the remaining two.
Real-Time Computation
Calculations update instantly as you type numbers or click preset test configurations.