Ohm's Law Calculator
Calculate voltage, current, resistance, and power using Ohm's Law relationships
About this calculator
The Ohm's Law Calculator is an essential tool for electrical engineers, students, and technicians that instantly calculates voltage (V), current (I), resistance (R), and power (P) using fundamental electrical relationships. Based on Georg Ohm's foundational law (V=IR) and power formulas, this calculator eliminates manual calculations and reduces errors when designing circuits, troubleshooting electrical problems, or completing homework assignments. Whether you're determining the correct resistor value, calculating power consumption, or analyzing circuit behavior, this tool provides accurate results for any two known electrical parameters.
How to use
Enter any two known values from voltage, current, resistance, or power into the corresponding input fields. The calculator will automatically compute the remaining two unknown values using Ohm's Law and power relationships. Clear results are displayed instantly, showing all four electrical parameters with appropriate units (volts, amperes, ohms, and watts).
Frequently asked questions
What is Ohm's Law and why is it important?
Ohm's Law states that voltage equals current times resistance (V=IR). It's fundamental for understanding electrical circuits, designing electronics, and solving electrical problems safely and effectively.
Can I calculate power using only voltage and current?
Yes, the calculator uses multiple formulas including P=VI, P=V²/R, and P=I²R to determine power and other values from any two known electrical parameters.
What units should I use in the calculator?
Use standard electrical units: volts (V) for voltage, amperes (A) for current, ohms (Ω) for resistance, and watts (W) for power to ensure accurate calculations.