Rest the object on the zero line. Hover the ruler, or drag on the blank area to measure between two points.
Online ruler
A centimetre ruler fixed to the left edge as soon as the page opens. The scale is estimated automatically, then you can match a bank card.
How to use the ruler
- 1. Set the browser zoom to 100%.
- 2. The left ruler is already on screen. On a known phone the scale is estimated from the resolution; on a computer it starts from the browser centimetre.
- 3. Press Calibrate and match the 85.60 mm edge of a bank card if the length must be exact.
- 4. Rest the object on zero. Drag on the white area to measure between two points.
Can the scale be automatic?
A browser knows pixels, not millimetres. This page estimates the scale as soon as it loads: known phone sizes use the screen diagonal, other screens use the CSS centimetre. That guess is saved in this browser until you match a card. The card is the measurement that makes 1 cm real on this display.
Does the online ruler show a real centimetre?
After calibration, yes, on this screen. Before that, the scale is an automatic estimate. Match a bank card’s 85.60 mm edge once.
Why is the ruler on the left?
The centimetre ruler is fixed to the left edge from the first view, with zero at the top. You do not scroll to find it.
Where is 1.6 cm on a ruler?
It sits between 1 cm and 2 cm, six millimetre marks past the 1 cm line.