Ohm's Law Calculator
Enter any two values — voltage, current, resistance, or power — and leave the other two blank to solve for them.
How This Calculator Works
This tool uses Ohm's Law (V = I × R) along with the power formula (P = V × I) to solve for any two unknowns once two values are known. Fill in any two fields — say, voltage and resistance — and leave the rest blank to calculate current and power automatically.
New to the formula itself? Read Ohm's Law Explained for a full walkthrough, or use the LED Resistor Calculator to size a resistor for an LED specifically.