online ruler
measure small objects on your screen. calibrate once with a bank card for accurate real-size marks.
runs on your device · free · no sign-up
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frequently asked questions
how accurate is it?
after calibrating with a standard card (85.6 mm wide) it is accurate to about a millimetre.
why calibrate?
browsers cannot know your screen real pixel density, so a known object sets the scale.
is the calibration saved?
yes, on this device only.