Online ruler in actual size, centimetres and inches
We could not identify this screen.
Why a screen ruler needs calibrating
No browser can ask a screen how big it physically is. That number is not available to a web page at all. So every screen ruler works the density out some other way, and every one of them is guessing to some degree.
We recognise your screen from its pixel signature. That is exact on iPhone and iPad, close on Android, and unreliable on laptops and external monitors, where the same resolution can be a 13 inch laptop or a 32 inch display. When we are not sure we say so, rather than showing a confident wrong answer.
In pixels the rule is exact on every device, because a pixel is the one unit a browser does know.
Why ads? They keep this free. Rather help another way?
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How it works
Measure something flatPut its corner in the corner of the rule. Read both scales.
Lift it onto the glassPress and hold the grip in the corner, then drag. Paper sits better on the screen than against the bezel. A stray touch anywhere else moves nothing.
RotateSends the rule to the next corner, so it is never under the thumb holding your phone.
Full screenHides the browser bars and gains you about a centimetre. Not on iPhone, where Safari has no full screen mode.
Longer than the screenA phone shows about 14 cm. Mark the spot, slide the object along, add the two readings. Or print a ruler instead.
LockFreezes every control while you measure. Unlock sits in the opposite corner, away from the hand holding your object.
Controls locked
Set the scale with a bank card
Every bank card is 85.60 by 53.98 mm. Hold one on the outline and move the slider until they match.
Now reading 96 pixels per inch
Too wide for this screen. Try the other orientation.