Ohms Law Calculator

Use it when your task matches one of these common needs: Find resistance from voltage and current. Find current from voltage and resistance. It works best when you already know the measurements, amounts, units, or options the page asks for.

In plain language: The calculator uses V = I x R and P = V x I after the missing voltage, current, or resistance value is solved. The examples on the page are there so you can compare your inputs with a worked example before copying the answer.

Voltage V: electrical potential difference, measured in volts. Current A: electrical flow through the circuit, measured in amps. Resistance ohms: how much the component or circuit resists current flow. Power W: energy rate, calculated after voltage and current are known.

Read the headline answer, then check the supporting lines and examples to understand how the calculator got there. If one input changes, rerun the tool and compare the new answer instead of guessing.

This is simple DC or resistive-circuit math. AC circuits, impedance, heat, component ratings, and electrical safety require more care. Also check the unit, scale, mode, and result limit because small input changes can change the answer.

Ohm law connects voltage, current, and resistance. If you know any valid pair, the calculator can solve the missing core value and then calculate power from voltage times current.

No. The calculator runs in your browser tab. Your recent answers stay only on the page while you use it, and they are not sent to a server.