Paper Sizes

ISO Paper Sizes

The ISO family of paper is commonly used in Europe. It uses a single aspect ratio for all sizes in its range. Most paper is in the A Series. It is defined by ISO 216.

A Series

A0 is one square meter, with the sides forming a ratio of 1:14142 (1:√2, or one to the square root of two). Each smaller size of paper is half of its predecessor, divided on the longer edge, retaining this ratio. The short side of one size becomes the long size of the next smaller one. This allows for consistent steps up and down. Enlarging or reducing on a copier makes for consistent steps with no blank space.

While it’s less common in the United States, I prefer it, if only for the geeky logic behind it. I also find that ISO paper sizes are what is typical for the most fountain pen friendly paper.

Size Inches Millimeters Notes
A0 33.125 x 46.8125 841 x 1188 The origin. One square meter
A1 23.375 x 33.125 594 x 841
A2 16.5 x 23.375 420 x 594
A3 11.75 x 16.5 297 x 420 Close match to “tabloid” paper
A4 8.25 x 11.75 210 x 297 Close analog to “letter.” A bit narrower and taller.
A5 5.875 x 8.25 148 x 210 “Junior” size paper. Most journals are this size.
A6 4.125 x 5.875 105 x 148 Good pocket notebook size
A7 2.9375 x 4.125 74 x 105 A good, if smaller, notebook size
A8 2.0625 x 2.9375 52 x 74 ISO-sized business card

Hypothetically, you can keep halving the paper until you reach some atomic size.

B Series

The B series is used to fill some gaps in the A series. It uses the same ratio, but based on geometric mean of two a sizes. It has the same It’s used to fill gaps between sizes of A. It’s less common, but does come up for some stationary.

Size Inches Millimeters Notes
B0 39.4 x 55.7 1000 x 1414
B1 27.8 x 39.4 707 x 1000
B2 19.7 x 27.8 500 x 707
B3 13.9 x 19.7 353 x 500
B4 9.8 x 13.9 250 x 353
B5 6.9 x 9.8 176 x 250 Books, some journals
B6 4.9 x 6.9 125 x 176 Books, some journals
B7 3.5 x 4.9 88 x 125 Passports ISO 7810, ID-3
B8 2.4 x 3.5 62 x 88 Playing cards
B9 1.7 x 2.4 44 x 62
B10 1.2 x 1.7 31 x 44

C Series

The C series is the geometric mean between the A and B series of the same number. It is used for envelopes. C4 is a bit larger than A4, and can fit a sheet unfolded. A C5 envelope can hold an A4 sheet folded in half, and so forth.

Size Inches Millimeters Notes
C0 36.1 x 5.11 917 x 129.7
C1 25.51 x 36.1 648 x 917
C2 18.03 x 25.51 458 x 648
C3 12.76 x 18.03 324 x 458
C4 9.02 x 12.76 229 x 324
C5 6.42 x 9.02 163 x 229
C6 4.49 x 6.38 114 x 162
C7 3.19 x 4.49 81 x 114
C8 2.24 x 3.19 57 x 81
C9 1.57 x 2.24 40 x 57
C10 1.1 x 1.57 28 x 40

North American Paper Sizes

Unlike the ISO standards, the North American sizes have no real rhyme or reason. Rather, they are based on a quixotic choice made by paper makers a long time ago. Generally, you will encounter Letter size, with most “journals,” like Moleskine are roughly half-letter sized.

Size Inches Millimeters Notes
Letter 8.5 x 11. 215.9 x 279.4
Legal 8.5 x 14. 215.9 x 355.6
Tabloid/Ledger 11. x 17. 279.4 x 431.8
Junior Legal 5. x 8. 127. x 23.2
Half-Letter 5.5 x 8.5 139.7 x 215.9
Government Letter 8 x 10 203 x 254 Perscribed by Hoover; Reagan went back to “normal” letter.
Executive 7.25 x 10.5 184.15 x 266.7
Business Card 3.5 x 2.0 89 x 51

Other Sizes

This covered the most common, general purpose paper sizes. There are some that are unique to different countries, proprietary to a specific manufacturer, or some other custom application.

Size Inches Millimeters Notes
Field Notes 3.5 x 5.5 89 x 140 Original "Kraft" pocket-sized notebook
"Sawed Off A4" 8.25 x 11 210 x 279.4 My custom size--an A4 sheet cut to US Letter height, to fit in US binders.
B6 Slim 4.2 x 6.9 106 x 174 I've seen this used in some planners, such as the Kokuyo Jibun Techo, as well as other notebooks.
A5 Slim 5.4 x 8.6 136 x 218 Anohter "slim" offered for the Kokuyo Jibun Techo. I haven't seen it myself.

References

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Last updated on January 7, 2024.
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