Electrical calculator
Ohm’s Law Calculator
Enter any two known values and calculate voltage, current, resistance and power.
Core relationships
Voltage = current × resistance
Power = voltage × current
The calculator rearranges those relationships depending on which two values you enter.
Worked example
A 12 volt circuit drawing 0.5 amps has 24 ohms of resistance and uses 6 watts of power.
Common mistakes
- Entering milliamps as amps.
- Entering kilohms as ohms.
- Assuming a real component holds the same resistance under every condition.
- Ignoring the component’s power rating.
This is basic electrical math
It does not determine whether a circuit is safe, code compliant, stable, insulated correctly, or suitable for the power source.