How to use the ohm's law calculator
Find voltage, current or resistance and power in a circuit. Enter voltage, resistance in the fields above; the current, current, power are computed instantly and plotted on the chart so you can see how the answer changes.
Formula
Variables
- V — Voltage (V)
- R — Resistance (Ω)
Worked example
With voltage = 12 V, resistance = 470 Ω, the calculator gives current ≈ 0.02553191 A; current ≈ 25.53191 mA; power ≈ 0.306383 W.
Frequently asked questions
What is the formula for the ohm's law calculation?
Current (A) = V / R. Current (mA) = [Current] × 1000. Power (W) = V × [Current]. Here V is voltage (V), R is resistance (Ω).
What inputs do I need for the ohm's law calculator?
You need voltage in V, resistance in Ω. Each field is pre-filled with a typical example so you can see how the result responds as you edit the numbers.
How do I use this calculator?
Type values into the input fields. Results and the chart update instantly. Use Reset to restore the example values, Copy results to paste them elsewhere, or Share to copy a link that preserves your inputs.
Is the result exact?
Calculations use standard formulas and double-precision arithmetic, then display about seven significant figures. Real-world measurements carry uncertainty, so treat results as estimates unless your inputs are exact.