Science & physics

Ohm's law calculator

Enter any two of V, I, R and P and get the other two.

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How it works

V = R × I and P = V × I. Leave the two values you want to find empty.

Results are for guidance only and do not replace professional advice.

Worked example

With the default values:

Voltage V (volts)12
Resistance R (ohms)220

you get:

Current I54.5455 mA
Voltage V12 V
Resistance R220 Ω
Power P654.5455 mW

Frequently asked questions

How does the “Ohm's law calculator” tool work?

V = R × I and P = V × I. Leave the two values you want to find empty.

What do I need to enter?

Just fill in: voltage v, current i, resistance r, power p. The result updates as you type.

Can you give an example?

Voltage V (volts): 12; Resistance R (ohms): 220 → Current I: 54.5455 mA; Voltage V: 12 V.

Is this calculator free, and is my data private?

Yes. HOD Calc is completely free with no sign-up. The calculation runs in your browser: nothing you type is sent or stored.