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Paper and Books

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Paper sizes (metric)
Paper sizes (old English)
Book sizes

Measurement: Paper and Books

This is not really Science, but it is Measurement.

Metric paper sizes (ISO 216)

A sizes are forPaper
B sizes are forPosters
C sizes are forEnvelopes
A3420mm x 297mm
A4297mm x 210mm
A5210mm x 148mm

Note that the long side on each size is the same length as the short side on the next largest size, and the short side on the smaller size is half as long as the long side on the larger size. And this is why each size is half the size of the next largest (see below). For other sizes (A0 to A2 and A6 to A10) you can extrapolate; where necessary, round down to the nearest whole number of millimetres.

The ratio between the long and short sides of an ISO standard sheet of paper Click to show or hide the answer

This explains the relationship between the long and short sides on the different sizes, and why (as we saw above) each size is half the size of the next largest. (Or, it is explained by that relationship; it's a bit of a chicken and egg situation.) For example: let the short side of a sheet of A4 be represented as x; the long side is √2 times x. Let's call this y. If we make the short side twice as long – 2 times x – this is now √2 times as long as the long side of our original sheet of A4 – because x times √2 times √2 is 2 times x. Or, to put it another way: if y = √2 times x, 2 times x is √2 times y.

And that, if you like, is actually science!

Old English paper sizes

This section is here simply because you might occasionally get asked something like "What do Pott, Post, Copy and Albert have in common?"

Its source is the British Association of Paper Historians (BAPH). The subheadings are the BAPH classifications; I've given a selection of the sizes it lists – leaving out other sizes which are based on these, e.g. Double Pott, Foolscap and Third, Double Large Post.

All dimensions are in inches. They're included as background information only; any question setter who names a size and asks for its dimensions (or vice versa) is having a laugh. The BAPH, in any case, says that they (and indeed the list itself) are "intended as a guide only and not to be taken as definitive".  Note that in different categories, the same name will have different dimensions.

I've highlighted each name the first time it occurs. (I haven't highlighted the ones that are based on other sizes – e.g. Pinched Post and Super Royal – because they're literally only here to make up the numbers.)

Writing Papers

Pott (12½ x 15) Foolscap (13¼ x 16½) Pinched Post (14½ x 18½)
Post (15¼ x 19) Copy (16¼ x 20) Medium (18 x 22½)

Cut Writing Papers

Albert (6 x 4) Duke (7 x 5½) Duchess (6 x 4½)
Foolscap (13 x 8) Small Post (9 x 7) Large Post (10 x 8)

Foolscap can be Folio or Quarto; the sizes given above are for Folio. Large and Small Post can each be Quarto or Octavo; the sizes given above are for Quarto.

Book and Drawing Papers

Foolscap (14 x 18¾) Demy (15½ x 20) Medium (17½ x 22½)
Royal (19 x 24) Imperial (22 x 30¼) Elephant (23 x 38)
Atlas (26¼ x 34) Columbier (23½ x 35) Antiquarian (31 x 53)

Printing Papers

Crown (16¼ x 21) Demy (17¾ x 22½) Medium (18¼ x 23)
Royal (20 x 25) Pott (15 x 25) Foolscap (17 x 27)

Cartridge Papers

Foolscap (14 x 18¾) Demy (17¾ x 22½) Royal (19 x 24)
Super Royal (19¼ x 27½) Imperial (21 x 26) Elephant (23 x 28)


Royal (20 x 25) Postal (22½ x 28½) Imperial (22 x 30)
Large Imperial (22 x 32) Index (25½ x 30½)

Many of the above sizes have metric equivalents: e.g. Metric Crown, Metric Demy, Metric Royal.

Foolscap (8.5 x 13.5 inches, 216 x 343 mm) got its name from its standard Click to show or hide the answer

Book sizes

Another site, apparently produced and maintained by an enthusiastic amateur and known as, explains book sizes. It lists three folio sizes (a folio being a complete, unfolded sheet of paper):

Royal Folio 20" x 12.5" Medium Folio 18" x 11.5" Crown Folio 15" x 10"

For each of these there are a number of smaller sizes, created by repeatedly folding the folio sheet.  Thus if the sheet is folded once it gives four pages and this size is known as quarto.  Folding twice gives eight pages, hence octavo.  Trussel lists sizes down to sixty–fourmo, although these are so small as to be impractical.

Books are often advertised as duodecimo – which can't be obtained by simply folding in half, but comes between octavo and sixteenmo.

The above is clearly an over–simplification – books nowadays come in all shapes and sizes, and they probably always have done. As with the BAPH paper sizes, book sizes are best seen as a guide only.

Just for completeness, the following table summarises – remembering that these are only a guide:

  Royal Medium Crown
Folio 20" x 12.5" 18" x 11.5" 15" x 10"
Quarto 12.5" x 10" 11.5" x 9" 10" x 7.5"
Octavo 10" x 6.25" 9" x 5.75" 7.5" x 5"
Duodecimo 6.25" x 6.7" (approx) 5.75" x 6" 5" x 5"

This suggests that a duodecimo book ought to have pages that are almost, if not exactly, square.  In my experience this is not the case. But as stated repeatedly above, these are only guidelines.

This is obviously far more detail than you are ever likely to need in a quiz. And any question master who asks you about sizes smaller than duodecimo, or (as with paper sizes) names a size and asks for its dimensions (or vice versa) is having a laugh.

© Haydn Thompson 2017