About Us
Online Free Ruler is a free, accurate measuring tool that turns any screen into a real, actual-size ruler. We built it so anyone can measure in inches, centimeters, and millimeters instantly — without hunting for a physical ruler, installing an app, or creating an account.
What We Do
Our online ruler shows true-to-scale markings in your browser and calibrates to your specific screen, so one on-screen centimeter equals one physical centimeter. You can place rulers on any edge, drag to measure distances, drop guides, and switch between cm, inches, and pixels in a click.
Why We Built It
Most on-screen rulers ignore the fact that every display has a different pixel density, which makes their measurements little more than guesses. We wanted a genuinely accurate online ruler that respects your privacy, loads instantly, and works the same on a phone, tablet, or desktop.
Our Principles
We keep the tool fast, clean, and free. There are no trackers and no sign-ups. Everything runs locally in your browser, and your calibration is saved only on your own device. We are committed to accessibility, so the ruler works with a keyboard and screen readers too.