Ohms Law Calculator

Use this free Ohms law calculator to solve V, I, R, and P from common voltage-current-resistance pairs.

All tools

Research-backed assumptions Formula steps Examples included Private in-browser use

Voltage VCurrent A

Circuit values24 W

voltage and current

Voltage: 12 V
Current: 2 A
Resistance: 6 ohms

This is simple DC/resistive-circuit math. Real circuits can involve AC, impedance, heat, and safety limits.

Formula steps

Use Ohm law V = I x R to solve the missing core value.
Use power P = V x I after voltage and current are known.
Show voltage, current, resistance, and power together for checking.

How to use the ohms law calculator

Choose the pair of known values you have: V and I, V and R, or I and R.
Enter the two values and press Calculate circuit values.
Review voltage, current, resistance, and power together.
Use extra caution for live circuits, AC loads, heat, and component ratings.

Common uses

Find resistance from voltage and current.

Find current from voltage and resistance.

Find voltage from current and resistance.

Estimate power after the core values are known.

Examples

Voltage and current 12 V and 2 A

6 ohms and 24 W

Current and resistance 2 A and 6 ohms

12 V and 24 W

Voltage and resistance 9 V and 3 ohms

3 A and 27 W

Frequently asked questions

Plain-language answers about when to use the tool, what it does with your inputs, what to double-check, and how privacy works.

When should I use the 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 values, dates, units, or settings the page asks for.

What is the Ohms Law Calculator doing with my inputs?

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 filled-out calculation before copying the answer.

What should I double-check before trusting the answer?

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

Does the site save what I enter?

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.