About Ruler Online Free

Ruler Online Free is a free, no-login online measuring toolkit. Use the online ruler to measure objects directly on your screen in centimeters, millimeters, and inches; grab printable rulers and a protractor; or work out your display's pixel density with the PPI calculator.

It runs entirely in your browser and works on desktop, tablet, and mobile. Nothing is uploaded — your calibration is stored locally on your own device.

A note on accuracy

On-screen measurements are only as accurate as your calibration. Screens vary in pixel density, so set your browser zoom to 100% and calibrate the ruler against a known object (such as a credit card) before relying on a measurement. The printable rulers are true-to-size only when printed at 100% / Actual Size.