What is Ohm's Law?

Ohm's Law is a fundamental principle in electrical engineering and physics that describes the relationship between voltage, current, and resistance in an electrical circuit. It states that the current passing through a conductor between two points is directly proportional to the voltage across the two points. Using our Ohm’s law calculator online free, you can quickly solve for any of the missing variables if you know at least two values.

How to Use This Online Calculator

To use this tool, simply input two known values into the corresponding fields (Voltage, Current, Resistance, or Power). The calculator will use the standard formulas (V=IR, P=VI) to derive the remaining two metrics. This is incredibly useful for DIY electronics projects, student homework, or professional electrical troubleshooting.

The Core Formulas

Depending on which values you have, our tool applies the following formulas:

• Voltage (V) = I × R
• Current (I) = V / R
• Resistance (R) = V / I
• Power (P) = V × I or I² × R

Frequently Asked Questions

Q: What are the units used?
A: This calculator uses standard units: Volts (V) for electromotive force, Amperes (A) for current intensity, Ohms (Ω) for resistance, and Watts (W) for electrical power.

Q: Can I use this for AC circuits?
A: This tool is designed for DC (Direct Current) circuits or purely resistive AC circuits. For complex AC circuits, you would need to account for impedance (Z) rather than just resistance.