British Imperial Paper Sizes

Before metrication the UK used British Imperial paper sizes, most of which were quickly superseded by the ISO 216 A series paper sizes, however Foolscap Folio, to give it its full name, the most commonly used office writing paper took longer to disappear. Foolscap was still in everyday office use well into the mid 1980's and the name was often, incorrectly, used to refer to A4 size paper. Foolscap can now only be obtained from specialist paper manufacturers such as James Cropper plc and is not available from commercial office supplies stockists.

Cut Writing Paper Sizes

The following table gives the sizes in inches and mm of the British imperial cut writing paper sizes.

Size	Width x Height (in)	Width x Height (mm)	Aspect Ratio
Albert	4.0 x 6.0 in	101.6 x 152.4 mm	1:1.5
Duchess	4.5 x 6.0 in	114.3 x 152.4 mm	1:1.3333
Duke	5.5 x 7.0 in	139.7 x 177.8 mm	1:1.2727
Foolscap Quarto	6.5 x 8.0 in	152.4 x 203.2 mm	1:1.2308
Foolscap Folio	8.0 x 13.0 in	203.2 x 330.2 mm	1:1.625
Small Post Octavo	4.5 x 7.0 in	114.3 x 177.8 mm	1:1.5556
Small Post Quarto	7.0 x 9.0 in	177.8 x 228.6 mm	1:1.2857
Large Post Octavo	5.0 x 8.0 in	127.0 x 203.2 mm	1:1.6
Large Post Quarto	8.0 x 10.0 in	203.2 x 254.0 mm	1:1.25

As can be seen from the above table the aspect ratios of the imperial paper sizes are not constant as per the ISO A & B series papers. Generally folio and octavo are longer and thinner and quarto paper is squarer than A series paper. Click the following link for detailed explanation of the difference between Foolscap and A4, Letter and Legal paper sizes in use across the world today.

Folio, Quarto & Octavo Paper Sizes Explained

Folio, Quarto and Octavo are all cut paper sizes and if used on their own are technically incorrect. For instance you may see the term folio paper - this could, and generally does, refer to Foolscap Folio however it could refer to Small Post folio. This is because the terms folio, quarto and octavo are used to define the number of folds used when the uncut paper is being folded after printing for binding into books.

Although some Folio, Quarto and Octavo sizes were available as loose cut paper (e.g. Foolscap Folio) most were only used in book printing. There are also some even less common folds sexto, duodecimo and sextodecimo that were almost exclusively used in book production. Below is a table of how folds translate into individual sheets (leaves) and pages (leaves printed double sided) for each type.

Name	Also Called	Folds	Sheets	Pages	Abbreviations
Folio	-	1	2	4	fo, f
Quarto	-	2	4	8	4to
Sexto	Sixmo	3	6	12	6to, 6mo
Octavo	-	3	8	16	8vo
Duodecimo	Twelvemo	4	12	24	12mo
Sextodecimo	Sixteenmo	4	16	32	16mo

Uncut Writing Paper Sizes

The following table gives uncut writing paper sizes from the British Imperial standards.

Size	Width x Height (in)	Width x Height (mm)	Aspect Ratio
Pott	12.5 x 15.0 in	317.5 x 381.0 mm	1:1.2
Double Pott	15.0 x 25.0 in	381.0 x 635.0 mm	1:1.6667
Foolscap	13.25 x 16.5 in	336.6 x 419.1 mm	1:1.2453
Double Foolscap	16.5 x 26.5 in	419.1 x 673.1 mm	1:1.6061
Foolscap and Third	13.25 x 22.0 in	336.6 x 558.8 mm	1:1.6604
Foolscap and Half	13.25 x 24.75 in	336.6 x 628.7 mm	1:1.8679
Pinched Post	14.5 x 18.5 in	368.3 x 469.9 mm	1:1.2759
Post	15.25 x 19.0 in	387.4 x 482.6 mm	1:1.2459
Double Post	19.0 x 30.5 in	482.6 x 774.7 mm	1:1.6053
Large Post	16.5 x 20.75 in	419.1 x 527.1 mm	1:1.2576
Double Large Post	20.75 x 33.0 in	527.1 x 838.2 mm	1:1.5904
Copy	16.25 x 20.0 in	412.8 x 508.0 mm	1:1.2308
Medium	18.0 x 20.5 in	457.2 x 520.7 mm	1:1.1389

As you can see from this table the true size of Foolscap is 13¼ x 16½ inches. The paper that used to be commonly used in offices, which was called Foolscap, was in fact the cut size Foolscap Folio.