Ohm's Law Calculator
Quickly calculate voltage, current, resistance, or power. Enter any two values and Sparky does the rest.
V = voltage (volts), I = current (amps), R = resistance (ohms), P = power (watts)
Enter any two values to calculate the rest.
Common formulas used
V = I × R
I = V ÷ R
R = V ÷ I
P = V × I
This calculator demonstrates the mathematical relationships in Ohm's Law for educational reference. It does not recommend or approve wire, breaker, equipment, or installation choices. Always follow electrical safety practices and applicable local requirements.
Related problems and reference
Planning and safety note
This content is for general learning and planning. Always verify work against current NEC requirements, manufacturer instructions, and local code rules. If you are unsure or see heat, sparks, burning smell, repeated trips, or damaged wiring, contact a licensed electrician.
For accurate readings and safe testing, having the right tools matters.See recommended tools →