Ruler for Laptop Screen
Turn your laptop's screen into a real ruler. Pick your exact laptop model or panel size for an accurate reading, or calibrate with a card.
Works best on a laptop or desktop with a mouse. On a phone, calibrate with a card or pick your exact model for the most accurate reading — auto-detect is a best guess.
Keyboard: C crosshair · A angle · D dark mode · F fullscreen · H hide controls · 1-4 units · Esc clear/close
More ruler units
Frequently asked questions
Does this work for MacBook and Windows laptops?
Yes — common MacBook Air/Pro sizes and typical Windows laptop panel + scaling combinations (13", 14", 15.6", including 1366×768 and 1080p at various zoom levels) are listed. Tap Calibrate → Device and pick the closest match.
My laptop isn't in the list — what do I do?
Switch to the Card tab and calibrate with any standard credit or ID card instead — that works accurately on any screen, listed or not. Everything — detection, calibration and measuring — happens entirely in your browser. Nothing is uploaded.
Why does screen zoom/scaling matter?
Windows display scaling (100%, 125%, 150% etc.) changes how many physical pixels make up each on-screen unit, so the same laptop can need a different calibration at different zoom levels — pick the entry matching your current zoom, or just use the Card tab to sidestep this entirely.