Letter – US Paper Sizes

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.

B+ or 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 round. 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.

Other paper size standards issued by ANSI include:

• ANSI INCITS 151-1987 – Bond Papers and Index Bristols – Common Sheet Sizes
• ANSI INCITS 96-1983 – Forms, Paper Sizes for Single-Part Continuous Business