The Screen Ruler is handy when you don't have a tape measure nearby — for example, checking whether furniture will fit in a space, estimating parcel dimensions against courier limits, quick measurements for DIY projects, or as a backup when you've left your tape measure behind.
Every phone screen has a different physical size and pixel density (PPI). Without calibration, the centimeter/inch readout will be inaccurate. After calibrating once with an object of known size (like a credit card), the result is saved for that device.
After calibration, measurement error is typically within 1–2 mm — sufficient for everyday estimates. For precision work (engineering, fine crafts), physical measuring tools are still recommended.
Centimeters (cm) and inches (in) are both supported and can be toggled to match your preference.
Full-screen mode hides the browser's address bar and toolbar, maximizing the usable measurement area on screen — especially helpful for longer objects, reducing both inconvenience and measurement error.
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