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About This Tool
The Ohm's Law Calculator solves for any unknown in the V = I × R relationship when you provide the other two values. Enter any combination of voltage (V), current (I in amps), or resistance (R in ohms) and the calculator finds the missing variable.
Ohm's Law is the foundational equation of electrical engineering. Every circuit analysis begins here, whether you're designing a simple LED circuit, sizing a resistor, or troubleshooting a power supply. The calculator also shows the power dissipation (P = V × I) as a bonus.
This tool is invaluable for electronics hobbyists, electricians, engineering students, and anyone working with circuits who needs quick, error-free calculations without reaching for a textbook.