The diagram is not to scale vertically: the real angular size is a fraction of a degree. The 1:1 scale is correct only if the display is not zoomed. The preview uses the colours selected on the left.
| Line | chars | width, mm | width, cm | squares | + margins | fits field |
|---|
One square = type size × 0.57 mm. Standard fields: short 13 squares, long 16, double short 24. Line widths are measured with the real metrics of the available typeface; Cyrillic and Latin are counted separately — take the widest language, not the first line.
| Information field | squares | width, mm | width, cm | slack |
|---|
The model accounts for the detection threshold only, corrected for crowding and contrast. Lighting level, observer movement and glance time are not part of it — allow a margin on site.