Writings in technical drawings

Important in writings in technical drawings is mainly the font size and line width (or line width). The basic rules for the implementation of fonts for technical drawings are in DIN EN ISO 3098-0 described. DIN 6774 are described in different font sizes.
As currently almost exclusively with CAD software worked, is the knowledge about the application of standard fonts in technical drawing has become relatively insignificant. For all that are still working without computer assistance (be it professionally or for training purposes), this basic particularly interesting.


Since there are different areas of application for fonts in technical drawings, there are also different font sizes. These are also dependent on subscription format and standardized according to DIN 6774. The font sizes are based on the used line group.

For fonts, there are groups of the line 0.5 and 0.7 (DIN 15) as well as at edges, dimensions and other elements in technical drawings. While the drawing formats DIN A1 and the use of A0 liner group 0.7 (with the base-line width 0.7 mm) is required, it can be for the formats A4 to A2 line between the two groups are free to choose.

Font sizes DIN 6774
font size font usage
Line Group
Line Group

2,5 mm 3,5mm


Tolerances, Rauhwertangaben, symbols, indexes, etc.
3,5 mm 5,0 mm


Lettering, dimensions, scale, etc.
5,0 mm 7,0 mm big Scripture plate, drawing no., Item numbers, marking of cuts, etc.

Basic rules for fonts in technical drawings

Besides the font size and line width are still some gaps and other dimensions for drawings in technical writings to be considered. What matters is the font size - in their orientation, all other dimensions of the lettering.

As explained above, the Relevant the font size, with the 'h' is marked. All other dimensions (a, b, c, d, e) are in a fixed relationship to the font size 'h'.

To illustrate these dimensions and the summary table, we simply as an example the line width d = 0.35 mm. With this line-width is a font size of 3.5 mm and therefore the values for the remainder font size:

  • a = 0,7 mm
  • b = 5 mm
  • c = 2,5 mm
  • d = 0,35 mm
  • e = 2,1 mm
  • h = 3,5 mm

With this example should be the correct implementation of labels in Technical drawings easily understandable.