About

Online Ruler is a free ruler for your screen. You calibrate it once with a credit card, a coin or your device size. After that it shows centimeters, millimeters and inches at real size. You pull guides out of the ruler to read a length.

Who it is for

Anyone who needs to measure a small flat object and has no ruler nearby: makers, sewers, jewelers, students, and people who shop online and want to check a size. It works on phones, tablets and computers. US users get inches with 1/16 marks. Metric users get cm and mm.

How it works

A web page does not know how big your screen is. So the tool asks you to match an object of known size, such as a credit card, to an outline. From that it works out the real size of a pixel on your screen. It saves this in your browser, one record for each screen. Before you calibrate, the ruler is an estimate and it says so.

The tool has limits. It is only as long as your screen. A calibration by eye is only as good as the match you make, so we add a check step with a second object. Read the notes on the actual size ruler page.

Privacy

Everything runs in your browser. We do not send your measurements anywhere. We do not ask you to create an account.

Who made this

This tool was built by Abhishek Mishra, a software development engineer (SDE) at Oqu AI, and is published by Bingemind.

Phone and WhatsApp: +91 63760 68337 (message on WhatsApp).

Contact