@Szabolcs The following might also help tex.stackexchange.com/q/9071/2693 (especially Leo's answer).

@AlanMunn I figured fancy header might be the answer. Now I just have to figure out how to adapt it to my use.

@AlanMunn Thank you, that's a good point. But I think I'll keep the header as-is

@Canageek hm, well... maybe just set the bottom margin to 1.5cm? ;-) It's a hack but if you just need to get this to look right on paper, it should work.

@DavidZaslavsky .... tests

@DavidZaslavsky Do you by any chance know how to prevent a Row[] from line-wrapping in Mathematica? It does that when I export to PDF. (If you don't, don't search for it)

@Szabolcs nope, I've actually never exported from Mma to PDF myself

@Canageek I'd suspect Adobe Reader: it's notorious for reducing pages to fit (even when they fit perfectly).

@YiannisLazarides: Why the late awarding of badges for you today?

@egreg I know; I had to turn that feature off; All the others are fine

@Canageek Actually that message wasn't aimed at you.

GRRRRRRRRRRRR. bottom = 2 cm gives 2.3 cm. But bottom = 1.75 cm gives ~1.6 cm.

@Canageek So \usepackage[letterpaper,margin=2cm]{geometry} should work. Unless it's a problem regarding A4 paper versus Letter. If you ask for info about the PDF, what are the dimensions shown?

@egreg I've seen cases where dvips has A4 paper as a default and other things have letter. This would consistently screw up the margins.

Page Size = 8.50 x 11 in

PDF Producer: pdfTeX-1.40.12

@canageek are you running TeXLive or MikTeX?

I think it is the page number at the bottom, since all the other ones are spot on. Also it could just be an artifact of the number of lines on the page not coming out to 2 cm; I bet that is it; If I have 1 extra line on the page then I get too small a margine, if I have 1 less then I get too large a margine, duhhh.

@Canageek If TeXLive, try tlmgr paper and check that every program returns "letter".

@AlanMunn TeXLive

@Canagreek are are you measuring the final margin by looking at the final printout? depending on your material TeX may be having trouble breaking the page and so leave it overfull or underful in which case th apparent margin is wrong (but the log file will tell all)

@egreg I always wondered why that doesn't cause problems with bar code (e.g. boarding passes). I guess bar codes must be scalable to some extent.

@DavidCarlisle Where in the log file should I be looking? I am betting that is the answer.

@Canageek overful vbox in output routine is an old favourite

Overfull \vbox (1.49593pt too high) has occurred while \output is active [] ? That seems to be a later page though.

@Canageek also make sure textheight is topsep plus an integer multiple of baselineskip otherwise you can't get a page full of text in to the page without something giving

@Canageek yes that's the one I meant:-)

@DavidCarlisle That's easy with geometry: pass it the option heightrounded

@DavidCarlisle I said screw it and changed the top margin to be 1.8 cm. The bottom one is close to 2 now, and it makes up for the whitespace LaTeX introduces via the fact it has titles (though admittedly very small ones, but I'm only 2 lines over.)

@Canageek My test gives exactly 2cm on each side.

Measured with suitable TeX rules, of course. :)

@egreg It is the fact that my page of text doesn't line up exactly with 2 cm margines, given how tall the text is, how large my title is, etc.

Question: I have a command \newcommand\foo[1]{\gdef\@foo{#1}} which is then called in a package (to set the default for \@foo). When I try to use \foo in the preamble, it has no effect, but when I use it after \begin{document} it works. Is there some obvious reason for this?

@egreg So if it puts 1 less line of text on screen I get a 2.3 cm margin, 1 more and 1.6 cm margin.

@Canageek the very first document I did in LaTeX had to have very exact spacing (as I was printing it on to a pre-printed form) I ended up using picture mode:-)

@Canageek My preamble is

\documentclass[12pt,letterpaper]{article}
\usepackage[margin=2cm]{geometry}

@AlanMunn Where is \newcommand{\foo}[1]{...}?

@egreg I also have \usepackage{tgtermes}, a title written out in \large and 4 section headers. :S I can give you the exact file but this isn't a MWE time, this is a 'fiddle with this damn thing' time. I think I've gotten it close enough.

@egreg In the package.

@AlanMunn So you say \usepackage{some}\foo{bar}? Add \makeatletter\show\@foo\makeatother just after the call to \foo

@AlanMunn what's \@foo really (is it a command reset by latex at begin document)?

@DavidCarlisle That's what I'm suspecting

@Canageek It should be irrelevant, if you don't load other packages that might do something to the pagination.

@egreg really? How would it fit the text on in that case? Also, yes, I have approximatly 1.5 zillion packages loaded. I figured it was just a case of ((font height)*(lines of text) + (space taken up by title) + (Space taken up by section titles) != 11 inches - 4 cm

@DavidCarlisle It's just \newcommand{\newclosing}[1]{\gdef\alan@closing{#1}}

(Just some shorthands for letters.)

@Canageek Use that call to geometry and don't do anything manually

@egreg Manually? What do you mean? Also I've gotten it close enough for my needs; If he complains I'll just point out that the section headers take up extra space and remove them, in which case it will easily fit on one page. Or I'll make a title page with nothing but my title and name, again which will make everything fit on one page.

@egreg I get the feeling that he was more worried about us handing him something with typefont 14, 1 inch margines and far, far too little text ;)

@Canageek If you need 14pt size then

\documentclass[14pt,letterpaper]{extarticle}
\usepackage[margin=2cm]{geometry}

@egreg No no, sorry. I was trying to say: I think he said 1 page, 2 cm margines not becuse he likes 2 cm margines, but becuse he has had students use '1 page' to mean 'almost no text' in past.

@Canageek Ok, so the preamble I showed you will give what you need. Exactly.

End of game, 3:0.

@Canageek You may be able to squeeze a line more by cleverly using \linespread. Or conversely, you can fit exactly the text you have so that it ends at the bottom

@egreg Nice idea, but I found moving the title into the top margin by 0.2 cm worked pretty well, and doesn't hurt my ethics since I don't need a title and could just move it to its own page.

@Canageek This is easy: do \vspace*{-0.2cm} before the title. Don't act on the margins set by geometry.

@AlanMunn What does \show\alan@closing say?

@egreg Oh. That would have been a good idea if I hadn't just emailed it to him. >.>

goes and adds that in case he asks for edits

@PauloCereda Phew! :)

@egreg In the preamble: undefined; after \begin{document} what it was set to in the package.

@Werner It appears as is some script, lost some rep. and got some badges, maybe for consolation:)

@AlanMunn I don't understand. You have \newcommand{\newclosing}[1]{\gdef\alan@closing{#1}} in the package mypack; you say \usepackage{mypack} and then \newclosing{Ciao} in the preamble. After this \show\alan@closing says "Undefined"?

@egreg Nice game. :)

@YiannisLazarides You win some, you loose some.

@egreg Sorry. I just figured out the problem. The \newclosing in the package is wrapped in \AtBeginDocument. That explains everything. No idea why I did that. Removing it solves the problem. Thanks.

@Werner Sure it is like that:)

@egreg: email sent. :)