Ohm Law Calculator
Ohm's Law Calculator works out Voltage and Current from Voltage, Current and Resistance. The default figures on this page give resistance of 6 ohm; change any entry and the result, the working and the sources update together.
Your figures
Updates as you typeHow this is worked out
4 steps
- Given voltage and current.
- V = 12 V, I = 2 A.
- R = V / I = 6 ohm
- P = V I = 24 W
Relations usedtable
Its 5 worked examples are re-run on every release, last on 15 September 2026. What changed
Sources and references
2 sources
What the Ohm's Law Calculator calculates
Solves Ohm's law and the power relation for voltage, current, resistance and power from any two known quantities.
How to use this Ohm's Law Calculator
Enter Voltage, Current, Resistance and Power. Voltage updates as you type, and “Use a worked example” loads checked figures you can adjust. Change one figure at a time to see what drives the result.
How the result is worked out
Open “How this is worked out” beside the result for the step-by-step calculation behind Voltage, Current and Resistance.
The method follows Ohm's law: V = I R, and the power relation P = V I and IEC 60050, International Electrotechnical Vocabulary.
Research R941-GT-1: 12 V across 2 A example
With Voltage: 12, Current: 2, the calculator returns Resistance: 6, Power: 24. This example is checked against an independent source in the test suite.
What you can compare
Change one input at a time to see how it affects Voltage, Current and Resistance. The inputs you can vary are Voltage, Current, Resistance, Power and Solve for.
Results are general information, not financial, tax, legal, medical or engineering advice. Check any decision that matters with a qualified professional.
See something wrong? Report a problem with this calculator
Frequently asked questions
How do I calculate ohms law?
Solves Ohm's law and the power relation for voltage, current, resistance and power from any two known quantities. Open “How this is worked out” beside the result to see each step for your own figures.
What are the 3 ohm's law formulas?
On the figures this page opens with — voltage 12 V and current 2 A — the resistance is 6 ohm. No single number fits everyone: change any figure above and the answer updates as you type, with each step of the arithmetic beside it.
How to calculate amps using ohms law?
It needs Voltage, Current, Resistance, Power and Solve for. Nothing else is required, and the figures stay in your browser.
What is the ohms law formula for resistance?
The result gives Voltage, Current, Resistance, Power, Conductance and Solved from, each labelled with its unit so the figure can be read on its own.
What information do I need for the Ohm's Law Calculator?
You need Voltage, Current, Resistance, Power and Solve for. The page opens with default figures that give resistance of 6 ohm, so you can see the scale before entering your own.
What does this Ohm's Law Calculator show?
It shows Voltage, Current, Resistance, Power, Conductance, Solved from and Relations used, with the working and any warnings for your entries.