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I'm trying to create a simple document, on letter paper with 1-inch margins all around. Here's the simple document I'm working with:

\documentclass[letterpaper,12pt]{report}
\usepackage[margin=1in]{geometry}
\begin{document}

\the\textwidth

\the\paperwidth

\end{document}

Given that letter paper is 8.5in by 11in (i.e., 612pt by 792pt), and the margins are 1in all around (i.e., 72pt on each side), I would expect the values of \textwidth and \paperwidth to be 612pt and 468pt respectively.

However, the actual result I get when I compile the above document is:

469.75502pt
614.295pt

I'm sure that some assumption I've made is incorrect, but I can't seem to find where I've gone wrong online. Can anyone explain why the actual results differ from my expectations?

CmdrMoozy
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  • Welcome to TeX.SX! You can have a look at our starter guide to familiarize yourself further with our format. – karlkoeller Dec 27 '13 at 19:51
  • Since the difference is so small it might be due to the difference between points and big points... – Bakuriu Dec 27 '13 at 20:00
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    There's a difference between "printers' points" (72.27 per inch) and "big points" (aka Adobe points), 72 to the inch. TeX uses the "printers' points" convention. – Mico Dec 27 '13 at 20:00
  • Since 1in=72.27pt and 614.295pt-469.75502pt=154.5399pt, you have 154.5399pt/2=72,2699pt=1in, so 1in margin. – karlkoeller Dec 27 '13 at 20:04
  • Is there a reference for this 72.27 figure? According to the Wikipedia article on points, the SI standard is 72pt = 1in, and the historical value found in "letter press printing" varied from 1pt = 0.18mm to 1pt = 0.4mm, and was never well-defined. – CmdrMoozy Dec 27 '13 at 20:05
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    the values for the units of measurement are specified in the texbook, p.57. possibly more accessible is victor eijkhout's "tex by topic" (texdoc texbytopic if you are using a tex live distribution), where these values are given on p.92 along with a bit of history. – barbara beeton Dec 27 '13 at 20:11

1 Answers1

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the values used for the units of measurement are specified in the texbook, p.57.

1 in = 72.27 pt (printers' points)
1 in = 72 bp ("big points" as adopted by adobe)

probably more accessible to people who haven't bought the texbook is victor eijkhout's "tex by topic" (texdoc texbytopic if you are using a tex live distribution, or available from victor's web site), where these values are given on p.92 along with a bit of history.

barbara beeton
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