Ohm's Law Calculator
Calculate voltage, current, resistance or power using Ohm's Law. Enter any two values to find the missing ones.
Input Values
Enter any TWO values to calculate the rest
Results
Enter any two values to calculate the rest
Ohm's Law Formulas
V = I × R
Voltage = Current × Resistance
I = V ÷ R
Current = Voltage ÷ Resistance
R = V ÷ I
Resistance = Voltage ÷ Current
P = V × I
Power = Voltage × Current
Understanding Ohm's Law
Ohm's Law describes the relationship between voltage, current, and resistance in an electrical circuit:
- Voltage (V): Measured in Volts — the electrical potential difference that drives current
- Current (I): Measured in Amperes — the flow of electrical charge through a conductor
- Resistance (R): Measured in Ohms (Ω) — the opposition to current flow
- Power (P): Measured in Watts — the rate of energy consumption or production
Common applications
- Calculating current draw for circuit design
- Determining resistor values for LEDs
- Sizing power supplies and batteries
- Troubleshooting electrical circuits
Example calculation
If you have a12V
power supply and a6Ω
resistor:
• Current:I = V ÷ R = 12V ÷ 6Ω = 2A
• Power:P = V × I = 12V × 2A = 24W