Sakes Alive! A4/A5
“Now we will switch from A3 to A4,” says Alejandro, the master papermaker here in Buenos Aires. I’ve seen paper being measured in A-scale before, mainly in the stationary and greeting card industries in reference to card and envelope size. Being from the US of A, I am familiar with paper described in Letter System dimensions, particularly my beloved 8.5″ x 11″, known outside the US as the “American Quarto.”
A 1979 US newspaper article, “Government after 58 Years, Standardizes Paper Size,” humorously reviews some of what’s known of the origin of the Letter System. In the 1920s, President Hoover appointed the Committee on the Simplification of Paper Sizes (I kid you not) to debate the official letter size. It was 1980 before The Joint Committee on Printing officially adopted a standard letter size of 8.5″ x 11″. Letter System dimensions are the official measurements of the US and Canada and consist of traditional sizes (with arbitrary aspect ratios) like Letter (8.5″ x 11″) and Legal (8.5″ x 14″).
image from BeLight Software
The terms A5, A4, A3, etc. are part of ISO paper measurement. The ‘IS’ here stands for ‘International System,’ meaning everyone else in the world. There is an A, B and C series with the A series being in greatest use and the A4 being the most popular size. Originally proposed in 1786 by German scientist and satirist Georg Christoph Lichtenberg, ISO works on an aspect ratio of one to the square root of two. (1:4142). The A series starts at A0 with the sheet measuring one square meter in area. Fold it in half and the resulting dimension is A1. Fold A1 in half and you have A2, etc. The sizes all have the same ratio which makes for ease in production, but also greater ease in reducing or enlarging images.
image from BeLight Software
ISO is gaining popularity in the United States. As much as I use and love the 8.5″ x 11″ size, I can see myself adopting the A system as a papermaker. To switch from A3 to A4 we just taped a divider to the deckle – easy cheesy! Switching sizes in the Letter System would require another mould entirely!
Check out the instructive Paper Sizes and Formats Explained: The Difference Between A4 and Letter from BeLight Software. It’s got all the details!
If you want even more, here is an amusing (albeit decidedly anti-Letter) video on the two systems:
One comment on “Sakes Alive! A4/A5”
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The Fiber Wire 
Altho’ the ISO system is so practical, I do like that you have Junior Legal for all those occasions when one finds it necessary to sue a child! 😉
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