Why use this calculator
Ohm's Law is the foundation of electrical engineering and electronics. This calculator helps you quickly determine any electrical parameter when the other two are known.
How to use it
Select what you want to solve for. For current: enter voltage (V) and resistance (Ω). For voltage: enter current (A) and resistance (Ω). For resistance: enter voltage (V) and current (A).
The formula
V = I × R (Voltage = Current × Resistance). I = V / R. R = V / I. Power: P = V × I.
Worked examples
12V battery, 100Ω resistor
0.12A (120mA) current, 1.44W power
When people use it
- Circuit design
- Electronics troubleshooting
- LED resistor selection
- Power supply calculations
Tips
- Always check units — volts, amps, ohms
- Power dissipation determines component ratings
- Use Kirchhoff's laws for complex circuits
Questions people ask
- What is Ohm's Law?
- Ohm's Law states that current through a conductor is directly proportional to voltage and inversely proportional to resistance. V = IR is the fundamental relationship.