US Paper Sizes

North America, including the US, Canada and parts of Mexico, is the only area of the first world that doesn't use the ISO 216 standard paper sizes, instead they use Letter, Legal, Executive and Ledger/Tabloid paper sizes and those that have been formalised in ASME Y14.1M - Metric Drawing Sheet Size & Format. US Envelope Sizes are also non-ISO 216 and are listed on this page. The following table gives the sizes in millimetres and inches of the Commonly used American paper sizes.

Size	Width x Height (mm)	Width x Height (in)	Aspect Ratio
Half Letter	140 x 216 mm	5.5 x 8.5 in	1:1.5455
Letter	216 x 279 mm	8.5 x 11.0 in	1:1.2941
Legal	216 x 356 mm	8.5 x 14.0 in	1:1.6471
Junior Legal	127 x 203 mm	5.0 x 8.0 in	1:1.6000
Ledger / Tabloid	279 x 432 mm	11.0 x 17.0 in	1:1.5455

The following page discusses North American paperweights in detail, as it is useful to know how weight, as well as the size and stock type, affects your choice of paper. The difference between US Letter and Legal Paper sizes and international A4 is discussed here, however, it is important to say that Letter is effectively the equivalent to A4 size in the USA.

ANSI Standard Paper Sizes

ANSI (American National Standards Institute) defined a regular series of paper sizes based around the Letter (8.5" x 11") format, with this becoming the A sizes and larger sizes being B,C,D & E. Surprisingly these ANSI standard sizes were defined in 1995 well after the ISO standard sizes. ANSI A sized paper is commonly referred to as Letter and ANSI B as Ledger or Tabloid.

Unlike the ISO standard sizes which have the single aspect ratio of 1:root2, ANSI standard sizes have two aspect ratios 1:1.2941 and 1:1.5455 which means that enlarging and reducing between the sizes is not as easy as with the ISO sizes and leaves wider margins on the enlarged/reduced document.

Size	Width x Height (mm)	Width x Height (in)	Aspect Ratio	Closest ISO
A	216 x 279 mm	8.5 x 11.0 in	1:1.2941	A4
B	279 x 432 mm	11.0 x 17.0 in	1:1.5455	A3
C	432 x 559 mm	17.0 x 22.0 in	1:1.2941	A2
D	559 x 864 mm	22.0 x 34.0 in	1:1.5455	A1
E	864 x 1118 mm	34.0 x 44.0 in	1:1.2941	A0

B+ (Super B)

B Plus, or Super B as it is sometimes known, has dimensions of 13" x 19" (329mm x 483mm). This size is the ANSI B size with a 1" margin for print bleed all the way around. It is sometimes known as A3+ or Super A3 in countries that use ISO 216 paper sizes. European manufacturers sometimes give this size as 330mm x 482mm.

Architectural Paper Sizes

North America also has a special series of paper sizes defined for architectural purposes, in general, these have aspect ratios of 4:3 or 3:2. These aspect ratios are very similar to the aspect ratio used for computer screens.

The following table gives details of the sizes for the architectural paper.

Size	Width x Height (mm)	Width x Height (in)	Aspect Ratio
Arch A	229 x 305 mm	9.0 x 12.0 in	4:3
Arch B	305 x 457 mm	12.0 x 18.0 in	3:2
Arch C	457 x 610 mm	18.0 x 24.0 in	4:3
Arch D	610 x 914 mm	24.0 x 36.0 in	3:2
Arch E	914 x 1219 mm	36.0 x 48.0 in	4:3
Arch E1	762 x 1067 mm	30.0 x 42.0 in	7:5