Ohms Law Calculator
Calculate voltage, current, resistance, or power using Ohm's Law.
Ohms Law Calculator
Calculate voltage, current, resistance, or power using Ohm's Law.
Engineering Calculation
ℹ️ Used for basic engineering ratio and product calculations
Disclaimer
Results provided by this calculator are for informational and educational purposes only. They are based on the values you enter and standard formulas, and should not be considered financial, medical, legal, or professional advice. Always consult a qualified professional before making important decisions based on these results. Roughtools makes no warranties regarding the accuracy or completeness of these calculations for your specific situation.
Frequently Asked Questions
Pro Tips
Always verify critical calculations with a second method or source — for important decisions, this tool provides a starting point, not a final answer.
Input accuracy determines output accuracy. Use precise values rather than rough estimates for the most useful results.
Run the calculation multiple times with slightly different inputs to understand the sensitivity of the result to your assumptions.
For professional, financial, medical, or legal decisions, always confirm results with a qualified professional before acting.
When to Use This Calculator
Use the Ohms Law Calculator for fast, accurate calculations without installing any software.
Understand the formula and see how changing inputs affects the result for educational purposes.
Get a quick estimate before performing more detailed analysis or consulting a professional.
Accessible from any device — no app to install, no account required, works offline after loading.
Run multiple scenarios quickly by changing one input at a time to understand sensitivities.
About the Ohms Law Calculator
This Ohm's Law calculator solves for any of the four fundamental electrical quantities — voltage (V), current (I), resistance (R), and power (P) — when you provide any two. Uses both Ohm's Law (V = I × R) and Watt's Law (P = V × I) to compute all four values simultaneously. Select your two known quantities, enter their values with units, and instantly see all four electrical quantities with the formulas used. Built for electronics students, hobbyists, electricians, and engineers.
How to Use the Ohms Law Calculator
- 1
Select the two electrical quantities you know (any two of V, I, R, P).
- 2
Enter the values with appropriate units (V, mA/A, Ω/kΩ, W/mW).
- 3
See all four quantities — voltage, current, resistance, and power — calculated instantly.
- 4
Review the formulas applied for each calculation.
- 5
Use for circuit design, component selection, and troubleshooting.
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