Ohm's Law & Power Calculator
Calculate electrical values using Ohm's Law (V=IR) and power equations. Find voltage, current, resistance, or power from any two known values.
Enter any two values to calculate the others
Calculate Any Electrical Value
Ohm's Law and power equations form the foundation of electrical engineering. Our calculator lets you find any unknown value (voltage, current, resistance, or power) when you know two others.
What is Ohm's Law?
Ohm's Law states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance. Combined with power equations, you can calculate any electrical parameter.
Ohm's Law & Power Formulas
V = I × R, P = V × I = I²R = V²/RWhy Use an Ohm's Law Calculator?
Quick Circuit Analysis
Instantly calculate missing values in electrical circuits.
Component Selection
Determine proper resistor values and power ratings.
Safety Calculations
Verify current draw doesn't exceed wire or component ratings.
How to Use the Calculator
Common Applications
LED Circuits
Calculate resistor values for LED current limiting.
Power Supply Design
Determine voltage drop and power dissipation.
Wire Sizing
Calculate current to select appropriate wire gauge.
Battery Life
Estimate runtime from power consumption and capacity.
Frequently Asked Questions
Voltage is measured in Volts (V), current in Amperes (A), resistance in Ohms (Ω), and power in Watts (W). The calculator handles conversions between milli, kilo, and mega prefixes.