Paper

METRICATION: 100% complete
	Metric	Non-metric
	Paper and card in millimetres
	Notepads and binders in ISO standard metric “A” sizes
	Envelopes in ISO standard sizes

Before metrication, the UK used imperial paper sizes. The most common sizes for writing purposes were Foolscap and Quarto.

Cut writing paper – Imperial sizes

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

Imperial paper sizes were replaced by the ISO 216 A series paper sizes in the 1970s.

A Series paper sizes

Size	Width x Height (mm)	Aspect Ratio
4A0	1682 x 2378	1:√2
2A0	1189 x 1682	1:√2
A0	841 x 1189	1:√2
A1	594 x 841	1:√2
A2	420 x 594	1:√2
A3	297 x 420	1:√2
A4	210 x 297	1:√2
A5	148 x 210	1:√2
A6	105 x 148	1:√2
A7	74 x 105	1:√2
A8	52 x 74	1:√2
A9	37 x 52	1:√2
A10	26 x 37	1:√2

The paper sizes bigger than A0, 4A0 & 2A0, aren’t formally defined by ISO 216 but are commonly used for oversized paper. The origin of these formats is in the German DIN 476 standard, that was the original base document from which ISO 216 was derived. 2A0 is sometimes described as A00, however this naming convention is not used for 4A0.

A Series Paper Size Definitions

The A series paper sizes are defined in ISO 216 by the following requirements:

• The length divided by the width is 1.4142.
• The A0 size has an area of 1 square metre.
• Each subsequent size A(n) is defined as A(n-1) cut in half parallel to its shorter sides.
• The standard length and width of each size is rounded to the nearest millimetre.