Ohm's Law Calculator

Enter any two of voltage (V), current (I) and resistance (R) to see the third value and the power P = V·I.

✓ Free to use

Voltage V

12 V

V = I · R

Current I

3 A

I = V / R

Resistance R

4 Ω

R = V / I

Power P

36 W

P = V · I

Upgrade to Light+ to add your school name.

Enter any two values

Fill in exactly two boxes — the third is calculated.

Voltage V (volts, V)Current I (amperes, A)Resistance R (ohms, Ω)

Upgrade to Light+ to add your school name.