Simple Online Ruler
Actual-size browser ruler in cm, mm & inches — no install
Free - Completely free to use; no account or download required.
About Simple Online Ruler
A free, browser-based actual-size ruler that displays centimeter, millimeter and inch markings at true physical size after simple calibration. Calibrate once using auto-detect, screen diagonal (in inches), or a credit card (85.60 mm) and switch freely between cm/mm/in on the same saved scale. Use it horizontally or vertically, requires no download or account, and is ideal for quick measurements when you don’t have a physical ruler.
Key Features
- Actual-size measurements in cm, mm and inches
- Three calibration methods: auto-detect, screen diagonal, credit card
- Save calibration and switch between horizontal/vertical orientations
- No download or account required; runs in-browser
- Guides on accuracy and calibration (PPI calculator and walkthrough)
Who is this for?
Designers, developers, makers, students and anyone needing quick, accurate on-screen measurements.
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FreeCompletely free to use; no account or download required.
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