Ohm's Law Calculator

Voltage · Current · Resistance · Power — enter any two

V = I × R

I = V / R

R = V / I

P = V × I = I²R = V²/R

Solve for

Common Ohm's Law Reference

Scenario	V	I	R	P
LED on 5V	5 V	20 mA	150 Ω	100 mW
MCU pull-up	3.3 V	330 µA	10 kΩ	1.09 mW
USB current limit	5 V	500 mA	10 Ω	2.5 W
9V battery load	9 V	100 mA	90 Ω	900 mW