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Ohm's Law Calculator

Enter any 2 of 4 electrical quantities — Voltage, Current, Resistance, or Power — and solve for the others instantly.

Fill in any 2 fields and click Calculate. Leave the fields you want solved empty.

⚡ V Voltage

〜 I Current

Ω R Resistance

⚙ P Power

Ohm's Law Formula Reference

Find	Formula 1	Formula 2	Formula 3
V (Voltage)	V = I × R	V = P / I	V = √(P × R)
I (Current)	I = V / R	I = P / V	I = √(P / R)
R (Resistance)	R = V / I	R = V² / P	R = P / I²
P (Power)	P = V × I	P = I² × R	P = V² / R

About Ohm's Law Calculator

Scientific calculations require precision and understanding of the underlying formulas. Ohm's Law Calculator provides both — letting you enter any 2 of 4 electrical quantities — voltage, current, resistance, or power — and solve for the others instantly with instant results and educational context. Perfect for homework, lab work, or quick engineering estimates.

How to Use

Enter your known values Fill in the input fields with the values you have. The tool will calculate the unknowns.

Select units if applicable Choose the correct units for your calculation to ensure accurate results.

Review the solution Check the calculated result along with any formulas, steps, or diagrams shown.

Explore different values Change inputs to see how different values affect the outcome. Great for building scientific intuition.

🔒 Privacy note: All processing happens locally in your browser. Your data is never sent to any server.

Why Use Ohm's Law Calculator?

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Verified Formulas Ohm's Law Calculator implements standard scientific formulas from physics, chemistry, and mathematics textbooks. Results you can trust for homework, research, and engineering.

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Step-by-Step Solutions Where applicable, see not just the answer but the calculation steps. Perfect for learning and verifying your own work.

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Instant Computation Complex calculations that take minutes by hand are solved in milliseconds. Explore different scenarios and parameters quickly.

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Great for Students Whether you're in high school physics or graduate-level engineering, Ohm's Law Calculator helps you check your work and build intuition for the underlying concepts.

Frequently Asked Questions

Ohm's Law states that the voltage (V) across a conductor is directly proportional to the current (I) flowing through it, with resistance (R) as the constant of proportionality: V = I × R. Named after Georg Simon Ohm (1827), it is one of the most fundamental relationships in electrical engineering.

Electrical power (P) is the rate at which electrical energy is transferred, measured in Watts (W). It can be calculated as P = V × I (voltage times current), P = I² × R, or P = V² / R. A 100 W light bulb on a 120 V circuit draws about 0.83 A of current.

In a series circuit, total resistance increases: R_total = R1 + R2 + R3. In a parallel circuit, total resistance decreases and is always less than the smallest resistor: 1/R_total = 1/R1 + 1/R2 + 1/R3. Adding resistors in parallel always lowers overall resistance.