More info & support the dev

Why I made it

I’m a woodworker and a coder and I can't ever seem to find a ruler outside my workshop. So I made one, Screen Ruler is a straightforward ruler, some roughly accurate calipers, a perfectly cromulent protractor, and a Bubble Level I'm actually rather proud of. The big thing is the ruler that can be calibrated against the screen already in your hand.

Find me online

Privacy & planned ads

Screen Ruler does not collect personal information: it does not ask for your name, email address, account, contacts or precise location, and its calibration preferences stay in your browser. If you choose the optional Online Device Match, the browser-provided device model hint and screen dimensions are sent to the matching service solely to identify the screen. If you explicitly save a device calibration, its model name or model code, display dimensions and adjusted scale are added to the shared calibration database; no account or contact information is attached. A short-lived one-way rate-limit token derived from the connection protects that database from spam. A small Google ad banner may appear at the bottom to help pay for the site. Google and its advertising partners may use cookies, IP addresses or similar identifiers for ad delivery and measurement; Google explains those practices in its advertising privacy information. Hold the settings button for five seconds to hide the banner for the rest of your visit.

How it works

Screen Ruler turns the screen’s pixel dimensions and a selected display diagonal into a calibrated scale. Its local phone presets are curated from openly licensed device-specification data, including the Global Smartphone Database 2025, alongside public manufacturer specifications and model-code aliases. It tries the model hint supplied by your browser first; if the local presets do not identify it, it can try a compatible shared calibration template before the optional MobileAPI third-party fallback. You can always select a device or calibrate manually instead.