Ohm's law calculator
Ohm's law ties together voltage, current and resistance; add the power relation and any two of the four quantities fix the rest. Fill in the two you know and leave the others blank.
Results
- Voltage
- —
- Current
- —
- Resistance
- —
- Power
- —
Results update as you type.
Formula
V = I × R
P = V × I = I² × R = V² / R
How it works
Voltage (V) is in volts, current (I) in amperes, resistance (R) in ohms and power (P) in watts. Currents in small circuits are often milliamps — enter 20 mA as 0.02 A.
The calculator waits until exactly two fields are filled, then solves the remaining two. If you overspecify (three or more values that disagree) it flags the conflict instead of guessing.
Want to see it in a real loop? The Ohm's law example puts a single resistor across a battery and reports the solved current straight from the MNA engine.