Ohm's Law Calculator
Enter any two of voltage, current, resistance or power — get the other two instantly.
Enter any two values — the other two are calculated (V = I×R, P = V×I).
Uses the first solvable pair in order (V&I, V&R, V&P, I&R, I&P, R&P). Clear a field to exclude it.
What Is the Ohm's Law Calculator?
The Ohm's Law Calculator is a free online tool that lets you enter any two of voltage, current, resistance or power — get the other two instantly. It runs entirely in your browser — your text and files never leave your device, so it's fast and private. There's nothing to install and no sign-up required.
How It Works
Using the Ohm's Law Calculator takes seconds. Paste or type your content into the input area (or upload a file where supported), adjust any options to fit your needs, and the result updates instantly. You can then copy the output to your clipboard, download it, or clear everything and start again. Because all processing happens locally with JavaScript, it works offline once the page has loaded.
When to Use It
Reach for the Ohm's Law Calculator whenever you need a quick, reliable way to enter any two of voltage, current, resistance or power — get the other two instantly. It's popular with writers, students, developers, marketers and anyone who works with calculators day to day. Bookmark it alongside the other Calculators in our toolbox so it's always one click away.
Frequently Asked Questions
- Is the Ohm's Law Calculator free to use?
- Yes. Every tool on the site is completely free, with no account, login or download required.
- Is my data private?
- Absolutely. The Ohm's Law Calculator processes everything locally in your browser. Your text and files are never uploaded to a server, so your data stays on your device.
- Does it work on mobile?
- Yes. The Ohm's Law Calculator is fully responsive and works on phones, tablets and desktops in any modern browser.
- Do I need to install anything?
- No installation is needed — it runs in the browser. We also offer an optional browser extension and mobile app for quick access to popular conversions.
Last reviewed: 2026-06-27