[Tex/LaTex] Why does LaTeX add 1 inch to margins

margins

LaTeX defines \topmargin, \evensidemargin and \oddsidemargin as follows: [reference]

\topmargin: Length of margin at top of page above all printing. 1 inch is added to this value.

\evensidemargin: Left margin on even numbered pages. 1 inch is added to this value.

\oddsidemargin: Left margin on odd numbered pages. 1 inch is added to this value.

Why is 1 inch added to each value?

Best Answer

(this is mostly from memory; i can't find most of the references in print or on line, although i know they exist somewhere.)

tex, as a system created in the u.s., was based on lettersize paper -- 8.5in x 11in.

in the original tex setup, now ensconced in plain.tex, the page size settings are \hsize=6.5in and \vsize=8.9in, which results in 1 inch margins (exact horizontally, and very close vertically) when a full page is centered.

in the early days, there was also a need to set a default location for the upper-left-hand corner of a page when it was to be printed. either at an early tug meeting at stanford, or perhaps in a discussion within the tex project group, it became clear that this would be arbitrary (although required). david fuchs (who was writing a key output device driver) stated, by fiat, that the origin would be set at 1 inch down, and 1 inch from the left edge of the paper. with no overwhelming objections, that became the default.

i can't prove it, but my guess is that latex simply followed the lead of tex itself in using this setting.