Two kinds of unit
Absolute units ignore the body size: pt, mm, cm, in. Relative units follow the current font: em is roughly an M, ex an x-height. Column commands tell you how wide this column is right now.
- pt
- A TeX point. 1 in = 72.27 pt. Hairlines and nudges.
- mm / cm / in
- Metric or inches. Avoid hard-coding figure widths in these.
- em
- Relative to the current font. Local gaps as 0.5em beat 4pt.
- ex
- Current x-height. Rarely used for figure width.
- mu
- Math units, in math only. Do not use mu in body \hspace.
Follow the column, not the paper
In a two-column venue layout, \textwidth is the full text block. \columnwidth and \linewidth are this column. A figure at width=0.48\linewidth sits beside another; 0.9\textwidth blows the column and overfulls both the preview and the submission PDF.
- \textwidth
- Full text-block width. For figure*, not a single-column plot.
- \columnwidth
- This column. Single-column figures in a two-column draft.
- \linewidth
- Current line width. Inside a minipage or list, this tracks the nested block.
- \linewidth 的 0.48 / 0.96
- About half for a pair; almost a full column for one. Leave a little for the gap.
What not to change in a venue draft
geometry, oddsidemargin, and \setlength{\textwidth}{…} fight the class. Over-length, crushed columns, and desk rejects often start here. If the layout is wrong, switch to the official template—do not patch margins in this file.
- Do not shrink the font or baselineskip to steal a line
- Do not sprinkle \vspace{-2em} around displays to fake page count
- If a float will not fit, shrink the graphic or the caption—not the margins
Local gaps
Separate paragraphs with a blank line, not a run of \\\\. If you must nudge, use a relative unit and touch only that spot.
- \hspace{0.5em}
- A horizontal nudge. Do not use it to align a whole table.
- \vspace{0.5ex}
- A vertical nudge. In a venue draft, resize the float first.
- \quad / \qquad
- Fixed math space. Do not indent body paragraphs with it.
FAQ
- Can I just set the figure to 8 cm?
- Switch venue or column count and 8 cm is too wide or too small. A fraction of \linewidth follows the shell.
- The preview looks soft. Is the image low-res?
- Check whether a bitmap is stretched past its pixels. Keep vector PDF figures, sized to the column, instead of rasterizing and then scaling up.