# Why does LaTeX add 1 inch to 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?

-
For a graphical representation of this, see p 10 (of section 3 Page layout) in the `layouts` documentation‌​. –  Werner May 16 '13 at 16:11
I suspect that a correct answer would be that the DVI format, which the original TeX produces, has no notion of the page size, or of the reference point on the page, so there is a need to fix a standard, which Knuth happened to fix at 1 inch from the top and left sides (probably because he's from the US and is used to measuring paper sizes in that crazy unit). Then one has to find why Lamport decided not to do the extra calculations needed to cancel those offsets. –  Bruno Le Floch May 16 '13 at 16:15
Just to check: are `\topmargin` etc part of TeX or part of LaTeX? –  John Wickerson May 16 '13 at 16:35
@JohnWickerson `\topmargin` is a latex-defined register (can't speak for the "etc" it depends which you mean) `\topskip` for example is a primitive as is `\voffset` –  David Carlisle May 16 '13 at 16:45
@DavidCarlisle Thanks, I just wanted to check that I was right to use "LaTeX", not "TeX", in my question. –  John Wickerson May 16 '13 at 17:10

(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.

-
downvote? may i ask why? –  barbara beeton May 16 '13 at 17:55
There is mention of old IMAGEN printers for which this offset was intended as it did not provide an offset itself (see the section on Offset fix from FSU's Computer Science department website). These printers were released in the 1980's and, I guess, were one of the first ones to become mainstream, causing the shift (literally). –  Werner May 16 '13 at 19:35
@Werner -- interesting link. but the text of "offset fix" explicitly says that that offset was included in the tex files to counter "a negative offset [that] was used on the PostScript printers to remove the initial offset." so these are two different, equal and opposite, offsets. (the imagen was a really nice printer, but it used liquid toner, which could be messy. ultimately, dry-toner printers won the day.) –  barbara beeton May 18 '13 at 12:08