Frequently Asked Questions
Everything you need to know about the Ohm's Law Calculator.
How does the Ohm's Law calculator work?
Enter the two values you know among voltage, current, resistance, and power, and it calculates the rest instantly.
Is it free?
Completely free, no sign-up, downloads, or limits.
What is Ohm's Law?
Ohm's Law states V = IR: voltage equals current times resistance.
Can it calculate power too?
Yes, using P=VI, P=I²R, or P=V²/R depending on which values you provide.
Does it handle different units?
Yes, each field has a unit dropdown (mV, kV, mA, kΩ, etc.) with automatic conversion.
Does it show the formula used?
Yes, along with a visual formula triangle and the substitution of your actual values.
What if I enter a negative resistance?
The calculator flags negative or zero resistance as physically invalid rather than returning a nonsensical answer.
Can I use this to check circuit homework?
Yes, it's designed for quickly verifying voltage, current, resistance, or power calculations.
Is my data stored?
No; everything runs in your browser and isn't stored or sent anywhere.
Does it work on mobile?
Yes, fully responsive with the formula triangle scaling to fit the screen.