What is the standard font height and type?

There is an international standard. The sizes of paper start at one square metre (A0), fold that in half you get A1, half again, A2, half again is A3 and half that is A4 – used for letters, notepads etc. Envelopes, shelves, binders, files etc are related to that. In engineering drawings, the font height is related to the stroke thickness as well as the paper size. This produces 2.5mm high letters with a stroke thickness of 0.25mm (the pen nib size) – this doubles up to 3.5mm/0.35 pen – which doubles up to 5mm letters using a 0.5mm pen – then 7mm/0.7mm. This makes life simple – an A0 sheet with a 5mm letter can be reduced 50% to A1 where the letters will appear 3.5mm, and so on. In perfect proportion. Now, to the font. back in the drawing board pen and pencil/ stencil days the international standard was for an IS font with an open 6 and 9, open 4, serif’d one, and barred seven. This was for legibility when reduced to microfilm, or badly reproduced by being fax’d or photocopied several times. These days this is known as ISOCPEUR in AutoCAD true type fonts. Never again does a blurry 6 look like an 8 or 9… before this font became available (Autodesk being an American company), Europeans/ Brits had to fudge things to get as close to ISOCPEUR as possible – this was settled more or less with Romantic Simplex (romans.shx) at a width factor of between 0.65 and 0.8. It was terrible, but the best we could do. Nowadays it is not necessary to use romans, romant etc., when the official font is available. Having said that, Arial seems to be the default for Revit – and while this used to crash pen plotters, and cause screen flickering when zoomed in (due to the font’s sharp edges), it’s no bother these days – it just uses a lot of ink and is a bit on the thick side when drawings are busy. I work in building services, and – like old fashioned maps do – it is useful to mix fonts to distinguish between the architect’s room names (Arial) and the services annotations (ISOCPEUR); different fonts help the readability of a busy drawing.

Edwin, text heights are the Pandora’s Box of CADD standards. We decided to set our text heights up so if you plot an ISO A3/ANSI B sheet at double size (ISO A1/ANSI D) and the same in reverse. It works for most cases and accommodates clients who ask for the other sized sheet after you have finished the drafting modeling.
Beyond developing a Global CADD Standard, the Australian Standards are constantly referred to as the go to standard for drafting in Australia; however it was written for drafting on the board, to accommodate the quality of handwriting and or the stencils (yes I am old enough to have useded those are Cad).
Cheers
Paul

Hi Edo,
I work for a Civil Engineering firm and we have gotten into the habit of using 1/8" (.125") simplex font for Proposed features and 1/10" (.1") with a lighter weight for existing features. This helps highlight proposed work and gives us that little bit of extra space for notes.

1/8" is not just a common standard, it is also just the correct size for reproduction. Meaning, not everyone generates a pdf and re-prints on a 1200×1200 full size plotter. Some companies still scan drawings (300dpi or smaller) and store in a Doc Management system for viewing or printing. Not all printers can plot 36", or are laser; not all monitors are large and connected to a nice CAD graphics card. Where I work, we developed our standards in the early 80's with small plotter dpi and small monitors and 1 full size company plotter and micro filming. We tested different sizes, but 1/8" worked the best.