Ohm’s Law Calculator
Enter any two of voltage, current, and resistance to solve for the rest and power.
Fill in any two; leave one blank.
Solve any Ohm’s law problem
Ohm’s law, V = I × R, ties together the three core quantities of any electrical circuit. Give this calculator any two of voltage, current, and resistance and it solves for the third, then adds the power dissipated.
Enter 12 volts across a 4-ohm load, for example, and it returns 3 amps and 36 watts. Leave any single field blank and the tool figures out which one to compute.
Accurate and private
It uses the exact Ohm’s law and power relationships, works in volts, amps, and ohms, and runs entirely in your browser.
Frequently Asked Questions
What does Ohm’s law state?
That voltage equals current times resistance, V = I × R. Knowing any two of the three lets you solve for the third.
How is power calculated?
From P = V × I, which also equals I²R or V²/R. The tool reports power alongside the missing quantity.
What units does it use?
Volts, amperes, and ohms, with power in watts. Enter values in those base units for consistent results.
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