Measure small things against your screen in centimetres and inches. Calibrate once with any bank card for an exact size.
loading toolHow to use the online ruler
- Open “Make the ruler exact” and match the box to a bank card (once per device).
- Place the object on the screen at the 0 mark.
- Tap or drag on the ruler to read the length.
Questions
Why calibrate?
Screens have different pixel densities, so browsers cannot know the real size. A card (85.6 mm wide) fixes that.
Is my data private?
Yes. Everything happens inside your own browser: nothing you type or choose is uploaded to us or anyone else.
Is it free?
Completely free, with no sign-up, no watermark and no limit on how many times you use it. Light ads keep the site running.
