How to use it
- Click “Calibrate for real size”, hold a bank card to the screen and match the outline.
- Choose cm or inches, horizontal or vertical.
- Put the object against the screen and read the measurement.
Questions and answers
Is the online ruler really actual size?
Only after calibration. Screens have different pixel sizes, so no website can know your real size on its own. A bank card is always 85.60 mm wide, which makes the calibration exact.
Does it work on a phone?
Yes. Calibrate on the phone too; a phone screen measures about 6 to 7 cm across, so turn on Vertical for longer objects.
How do I find my ring size?
Use “Measure a ring” with a ring that fits: the inside diameter gives the US size. Jewelers in other countries use their own tables based on the diameter or circumference.
What about camera rulers?
Apps like iPhone Measure use the camera and AR. This ruler uses the screen, which is more precise for small objects you can lay on it.