Ohm's Law Calculator

Ohm's Law Calculator is a clean, fast tool for solving DC circuits — completely offline. Enter any two of voltage, current, resistance and power, and it instantly works out the other two. Whether you are sizing a resistor for an LED, checking the current a kettle draws, or learning the formulas for the first time, you get the full picture the moment you type.

WHAT YOU CAN DO
• Enter any two of Voltage (V), Current (I), Resistance (R) and Power (P)
• Get all four values at once, clearly labelled with their units
• See at a glance which values you entered and which were calculated
• Load real-world examples — LED, kettle, resistor, USB charger, speaker, motor
• Learn the formulas behind every answer

THE MATH, DONE RIGHT
Every result comes from Ohm's law and the power equations: V = I x R, P = V x I, P = I squared x R and P = V squared / R, plus all of their rearrangements. Invalid input — like a zero where it would divide — is flagged with a clear message instead of a wrong answer or a crash.

LEARN AS YOU GO
A built-in Learn tab explains, in plain language, what Ohm's law is, how the power equations connect to it, and how the Ohm's-law wheel ties all twelve formulas together. Great for students, hobbyists, makers and anyone brushing up on electronics.

CLEAN AND FOCUSED
Light and dark themes that follow your system, a tiny download, and no clutter. No sign-in, no setup.

PRIVACY
The app collects no personal data and works fully offline — your inputs never leave your device. Ads are served by Google AdMob, which may use an advertising identifier as described in Google's policies.

IMPORTANT
This calculator is for educational and general use. Always follow proper safety practices when working with electricity, and consult a qualified electrician for real wiring and installation work.

Download Ohm's Law Calculator and solve any V, I, R or P with confidence.