[Tex/LaTex] Setting a document in MS Word-12pt (12bp)

fontsizemswordunit-of-measure

Warning

If you're looking for advice how to make your document look like it's been written in Word, this is most likely not the question you're looking for. This question is mostly of theoretical nature, as it results in tiny differences, which will most likely not be noticed by someone who doesn't allow the use of LaTeX.

Questions that might be more helpful for this matter are:

Question

I learned that MS Word uses a slightly different version of the unit "point" (pt) than TeX does:

The 12 point of Word will be PostScript point, which in TeX would be called 12bp. A TeX pt is slightly smaller: it's 1/72.27 inch, while a bp/PostScript point is 1/72 inch. See also http://en.wikipedia.org/wiki/Point_%28typography%29

(Martin Schröder in Latex commands for a specific page format)

I'm writing a paper that would usually be expected to be "typeset" in MS Word, thus I want to use the same font size as Word would.

How do I set a document e.g. in the "12pt" font size that MS Word would use?

In case it matters, I'm using the article document class, Latin Modern (lmodern) as a font with the T1 font encoding and compile with pdfLaTeX, but input on different set-ups is more than welcome.

Best Answer

As per the discussion, one way of achieving this goal is to redefine the "shorthand" length dimension used throughout the standard document classes. Here's an extract of the relevant code snippets from ltxplain.dtx containing the abbreviated definition:

\newdimen\p@ \p@=1pt % this saves macro space and time

As such, issuing

\makeatletter\p@=1bp\makeatother% or \setlength{\p@}{1bp}

modifies the default 1pt reference to 1bp. Looking at article.cls (although other document classes are similar), many related lengths are set using \p@. Here's an excerpt:

\setlength\lineskip{1\p@}
\setlength\normallineskip{1\p@}
...
\setlength\parskip{0\p@ \@plus \p@}
...
\setlength\arraycolsep{5\p@}
\setlength\tabcolsep{6\p@}
\setlength\arrayrulewidth{.4\p@}
\setlength\doublerulesep{2\p@}
...
\setlength\fboxsep{3\p@}
\setlength\fboxrule{.4\p@}
...
\setlength\abovecaptionskip{10\p@}
\setlength\belowcaptionskip{0\p@}
...
\renewcommand\footnoterule{%
  \kern-3\p@
  \hrule\@width.4\columnwidth
  \kern2.6\p@}
...
\setlength\columnsep{10\p@}
\setlength\columnseprule{0\p@}

including some macros like \maketitle and things associated with indexing. So, issue the size change before \documentclass in order to let the effect filter through. You would still "miss" some \p@-related definitions though, as may be seen by viewing latex.ltx.

As a quick way to check the difference in the default pt and modified bp measurements (in lmodern) is using printlen. Here's a brief example with focus on the character X:

enter image description here

\documentclass[12pt]{article}
\usepackage{lmodern}% http://ctan.org/pkg/lmodern
\usepackage{printlen}% http://ctan.org/pkg/printlen
\begin{document}
\uselengthunit{pt} \renewcommand{\arraystretch}{1.5}%
\setbox0=\hbox{\fontsize{12pt}{14pt}\selectfont X}% pt measurement
\setbox1=\hbox{\fontsize{12bp}{14pt}\selectfont X}% bp measurement
\begin{tabular}{ccc}
  X & width & height \\ \hline
  \verb!pt! & \printlength{\wd0} & \printlength{\ht0} \\
  \verb!bp! & \printlength{\wd1} & \printlength{\ht1} \\ \hline
\end{tabular}
\end{document}

The difference in width is around 0.04pt and 0.03pt in height, which translates to about 0.01mm - a roughly 0.3% increase (~ 72.27/72-1). This is virtually negligible to the naked eye at regular font sizes.

Paragraph construction is altered using 12bp rather than 12pt, and therefore also hyphenation. Here's an example showing the effect:

enter image description here

\documentclass[12pt]{article}
\usepackage[margin=0.5in]{geometry}% http://ctan.org/pkg/geometry
\usepackage{lmodern}% http://ctan.org/pkg/lmodern
\usepackage{lipsum}% http://ctan.org/pkg/lipsum
\begin{document}
\renewcommand{\arraystretch}{1.5}%
\begin{tabular}{p{0.4\linewidth}p{0.4\linewidth}}
  \verb!12pt! font & \verb!12bp! font \\ \hline
  %\fontsize{12pt}{14pt}\selectfont% pt measurement
  \lipsum[1] &
  \fontsize{12bp}{14pt}\selectfont% bp measurement
  \lipsum[1]
\end{tabular}
\end{document}
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