Questions
Is the online ruler accurate?
Only after calibration, because screens differ in pixel density. Match the outline to a bank card or enter your screen size, and it is accurate to about a millimeter over 10 cm.
How big is a bank card?
Bank cards, ID cards and most driving licenses use the ID-1 size: 85.60 × 53.98 mm, about 3.37 × 2.13 inches.
Can I measure in inches?
Yes. The top edge shows centimeters and millimeters, the bottom edge shows inches down to a sixteenth.
Do I need to calibrate every time?
No. The calibration is saved in this browser. Calibrate again when you use another screen.