Technical drawing pen sizes
Technical drawing pens follow the same size-ratio principle as A series paper sizes, that is, an aspect ration of 1:√2, with the progression proceeding by folding the preceding size in two. When an A size piece of paper is folded in two it retains it's proportions.
The standard sizes for technical drawings pens also differ by a factor √2, ie. 2.00 mm, 1.40 mm, 1.00 mm, 0.70 mm, 0.50 mm, 0.35 mm, 0.25 mm, 0.18 mm, 0.13 mm.
This means for example that after drawing with a 0.35 mm pen on A3 paper and reducing it to A4, you can continue with the 0.25 mm pen. (ISO 9175-1).
[edit] Find out more
[edit] Related articles on Designing Buildings Wiki
Featured articles and news
We have a great range of introductory articles written by ECA.
7 of the most common myths, busted.
Consider a career in the electrotechnical industry.
Exploring local assets of community significance. Book review.
Wood-burning stoves should not be used in thatch-roofed buildings.
Servitisation, smart systems and connectivity.
What happens to the Construction Products Regulation if there is no Brexit deal.
National Infrastructure Strategy
The first step to long-term prosperity.
The status and rights of employees in construction
Continuing to share environmental best practice.
Charity in the electrical sector
The employee assistance programme EAP.