Ohm's Law Calculator
Calculate voltage, current, or resistance using Ohm's Law. Enter any two values to solve for the third, plus power output.
V
A
Ω
Voltage
—
Current —
Resistance —
Power —
How to Use This Calculator
- Select what you want to solve for (Voltage, Current, or Resistance).
- Enter the two known values.
- Click Calculate to see the missing value and power output.
Formula
V = I × R | I = V ÷ R | R = V ÷ I
Power: P = V × I = I² × R = V² ÷ R
Example
Example: V = 12 V, R = 4 Ω → I = 3 A, P = 36 W.
Frequently Asked Questions
- Ohm's Law states that Voltage (V) = Current (I) × Resistance (R). It describes the relationship between these three fundamental electrical quantities.
- Use I = V ÷ R. Enter voltage and resistance; leave current at 0 and the calculator solves for it.
- Use R = V ÷ I. Enter voltage and current; set resistance to 0 and the result field shows the missing value.
- Voltage in Volts (V), current in Amperes (A), resistance in Ohms (Ω), and power in Watts (W).
- Power P = V × I = I² × R = V² ÷ R. The calculator always shows power alongside the solved variable.