Ohm's Law Calculator
Calculate voltage, current, resistance, and power using Ohm's Law (V = IR).
With 12V and 2A, the resistance is 6 ohms.
Why This Calculation Matters
The Ohm's Law Calculator computes a standard electrical quantity so you can focus on the problem, not the arithmetic.
How to Use This Calculator
- Enter your values in the input fields, each one has a label and help text explaining what to type.
- Results appear instantly as you type; there's no "calculate" button to press.
- Change any input to compare scenarios side by side.
All math happens in your browser. Nothing you type is sent to a server, saved, or shared.
Ohm's Law
The fundamental relationship between voltage, current, and resistance:
- V = I × R (Voltage = Current × Resistance)
- I = V / R (Current = Voltage / Resistance)
- R = V / I (Resistance = Voltage / Current)
- P = V × I (Power = Voltage × Current)
Enter any two values to calculate the rest.
Formula
V = I × R (voltage equals current × resistance). Power: P = V × I = I² × R = V² / R.
When to Use This Calculator
- Verify computations in physics, chemistry, or engineering problem sets.
- Pre-check experimental setups before running them in a lab.
- Back out unknown values when only partial data is given.
Limitations & Common Mistakes
- Results are estimates, real-world outcomes depend on factors not captured in a simplified calculation.
- Always verify critical numbers against an authoritative source or domain expert before acting on them.
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that the current through a conductor is directly proportional to the voltage across it and inversely proportional to the resistance. V = IR. It's the foundation of all electrical circuit analysis.
How do I use the Ohm's Law Calculator?
Enter your values in the input fields. Results update instantly as you type. Each input has a label and help text explaining what to enter.
How accurate is the Ohm's Law Calculator?
The calculator uses well-established formulas and is reliable for planning and comparison. For decisions with real financial, legal, or health consequences, also check with a qualified professional.
Is this calculator free to use?
Yes. The Ohm's Law Calculator is free, requires no signup, and runs entirely in your browser, your inputs are never sent to a server.
How often is this calculator updated?
Formulas are reviewed against authoritative sources, and any rate or price data is refreshed on an automated schedule. Check the "as of" date on any live data panel for the most recent refresh.
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