Input Parameters
Enter any two known values. The calculator will compute the other two.
About This Calculator
- Ohm's Law: V = I × R — enter voltage and current to find resistance and power
- Power Law: P = V × I — power is the product of voltage and current
- Auto-solve: Enter any two values. The calculator finds the remaining two.
- Precision: Results rounded to 2 decimal places for practical use.
How this Ohm's Law calculator works
Ohm's Law describes the relationship between voltage (V), current (I), and resistance (R) in an electrical circuit: V = I × R. Given any two of these values, the third can be calculated directly.
This calculator extends Ohm's Law with the power formula P = V × I, allowing you to find all four electrical parameters from just two known values. The calculator handles all six possible input combinations automatically.
Inputs explained
- Voltage (V): The electrical potential difference. Typical values: 12V (automotive), 120V/240V (residential).
- Current (I): The flow of electric charge. Measured in amperes. Typical values depend on the circuit.
- Resistance (R): Opposition to current flow. Measured in ohms. Typical values: milliohms to megaohms.
- Power (P): The rate of energy transfer. Measured in watts. P = V × I = I² × R = V² / R.
FAQ
What if I enter more than two values?
The calculator uses the last two fields you entered or modified. If values are inconsistent, the most recent inputs take priority.
Can I use this for AC circuits?
This calculator uses DC formulas. For AC circuits with reactive components, use our Power Calculator which handles power factor.
Why are my results showing "Infinity"?
This happens when you enter zero for current or resistance while trying to divide by it. Check your inputs — zero resistance means a short circuit.