Ohm's Law Calculator

Calculate voltage, current, resistance, or power from any two known values.

What Is the Ohm's Law Calculator?

Calculate voltage, current, resistance, and power using Ohm's Law. Enter any two values to find the other two instantly. Includes unit converter, series/parallel resistance calculator, and AWG wire reference.

How to Use

Using the Ohm's Law Calculator is simple:

  • Enter your values in the input fields
  • Click the calculate button
  • View your results instantly

Tips

  • Double-check your inputs for accurate results
  • This tool provides estimates - consult a professional for important decisions
  • Save your results for future reference

Frequently Asked Questions

What is Ohm's Law?+
Ohm's Law states that voltage = current × resistance (V = IR). It describes the relationship between voltage, current, and resistance in a circuit. If you know two of them, you can calculate the third.
How do I calculate power?+
Power (watts) = voltage × current (P = VI). Using Ohm's Law to substitute: P = I²R or P = V²/R. This is used for electrical systems and appliance ratings.
What happens to current if resistance increases?+
At constant voltage, current decreases as resistance increases (I = V/R). Doubling the resistance means half the current. This is why long extension cords (higher resistance) reduce current to devices.
Why is Ohm's Law important?+
It is the foundation of all electrical engineering. Designing circuits, selecting fuses, wiring, and ensuring appliances receive the right power all rely on Ohm's Law. Without it, electrical systems would be unpredictable and dangerous.

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