Paper Sizes Explained

unsharpen.com

7 pointsthomas3 comments

Regarding A, B and C ISO sizes, they aren't mysterious:

- the aspect ratio is square root of 2 to 1, so that cutting in half the long side leaves two sheets with the same aspect ratio.

- A is the main series, with A0 approximately one square meter.

- B sizes are square root of 2 times larger in area than A formats with the same numbers, filling the gaps.

- C sizes are slightly larger than A sizes, suitable for containers, envelopes etc. for them.

Markus Kuhn’s International Standard Paper Sizes¹ is a great document on ISO-216 paper sizes, if you want a little more depth than HelloNurse’s succinct description. It also covers US-style sizes toward the bottom.

Kuhn also has an excellent ISO-8601 document², which makes you wish he would dive through more of the common standards that ISO stand guard over.

¹ https://www.cl.cam.ac.uk/~mgk25/iso-paper.html

² https://www.cl.cam.ac.uk/~mgk25/iso-time.html - Sadly only covers timestamps, not durations/intervals/etc

Now I'm confused. The article says at one point that ANSI "letter" is 8 1/2 inches by 12 2/3 inches and also that "letter" size is 8 1/2 inches by 11 inches without explaining the discrepancy. So which is it?

Reply on news.ycombinator.com