Pens and Pencils | Reviews and Data

ISO Drafting Pencil Color-Coding Guide

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Did you ever notice that your drafting pencils have different color text printed on them? You might not know this, but those colors aren’t randomly assigned. The color-coding applies to mechanical pencils, but also to drafting pens, like the Rotring Isograph/Rapidograph, and was popularly seen on professional tools but not so much on consumer-focused items.

The color-coding, which was defined by ISO standard 128, is very simple and generally manifests itself on the pens and pencils we use everyday as:

  • 0.25 mm – white
  • 0.35 mm – yellow
  • 0.5 mm – brown
  • 0.7 mm – blue
  • 0.9 mm – red

Here is a more complete representation, based on a fully realized set of instructions from ISO 128-20:2001 Technical drawings – Part 20: Basic convention for lines:

Courtesy of Wikipedia

The Rotring Tikky mechanical pencils have ISO 3098 color-coding for easy lead width identification, as do the Staedtler Mars and Graphite 925 pencils, just to name a few.

Remember, these are a guideline, not a law, so some companies will follow the coding and others will not. Rotring, for example, makes excellent quality drafting pencils (like the Rotring 600) but doesn’t have any color indicator on the pencil at all.


What does ISO stand for?

ISO is the International Organization for Standardization. ISO is a non-governmental organization based in Geneva, Switzerland. It’s partnered with over 160 national standards bodies in order to create worldwide standards for all manner of products.