How RealLineal Works
A free, accurate ruler on your screen. Measure small physical objects at true 1:1 scale with no app or account needed.
Why We Built It
Finding a ruler when you need one is harder than it sounds. If you need to measure a small screw, a ring size, or a craft piece, you usually have nothing nearby.
Most online ruler images are not calibrated to your screen. Every display has a different pixel density, so a generic ruler image can be off by 30% or more.
RealLineal fixes this problem. With easy calibration, one centimeter or one inch on your screen becomes exactly one centimeter or one inch in your hand.
RealLineal was built by an independent developer who wanted a fast, private, and accurate measuring tool that works anywhere without ads or installs.
Simple Ways to Get True Size
Pick whichever method is easiest for you:
Check with Any Card
Every bank card, ID card, or transit card is standard size (85.6 mm). Hold your card to the screen, slide to match, and you are calibrated.
Pick Your Screen Size
Know your screen size? Click popular options like 13.3″, 14″, 15.6″, or 24″. The ruler instantly adjusts to your display.
CM, MM & Inches
Switch units anytime. Read metric ticks down to the millimeter, or use fractional inch marks, with draggable guide lines.
RealLineal runs entirely in your browser with no account, no software, and no tracking of what you measure. Your calibration is saved only on your device so it is ready whenever you return.