The Measure of a Column

What changes when a page is divided in two, and what must not

Adilson Carvalho

Sydney, 28 August 2026

Abstract Dividing an A4 page into two equal columns leaves 82mm of measure. At the single-column base of 11pt that carries 42 characters — below the floor at which a line of prose stays readable. This note works through what a two-column template must therefore change, and what it must leave alone.

The arithmetic

A4 is 210mm wide. Take off the standard margin, 20mm on each side, and 170mm of text width remains. A 6mm gutter divides it into two columns of 82mm.

At 11pt, an 82mm column carries about 42 characters. This specification sets 45 as the floor for a line of prose, so neither 11pt nor 10.5pt (44) is available here. Dropping the base to 9.5pt restores 49 characters, and every other step in the scale comes down with it.

What follows from the size change

Leading tightens from 1.45 to 1.4. A shorter line needs less vertical separation for the return sweep to stay unambiguous, and the saving is real: at 13.3pt of advance a column holds 54 lines instead of 45.

Headings come down hardest. A 24pt level-2 heading inside an 82mm column spends three lines saying two words, so the scale runs 20/13/11/9.5 — and the level-1 heading keeps display size only because it spans both columns.

What does not change

The colour palette, the rule weights, the numeral conventions, the treatment of quotations and the pagination rules are all identical. A template sets the page and the scale; it does not get its own typography.

Justification stops being optional

At 49 characters a ragged right edge serrates the column visibly, and the word gaps in an unhyphenated justified column read as rivers. Both faults are tolerable at 66 characters and neither is tolerable here.

This is the one place the spec removes a choice it otherwise offers.

So the two-column template turns justification on itself rather than offering it as an option. An implementation that offers ragged-right two columns is not conformant.

Spanning

An element spans both columns fully or neither. Spanning costs a break in both columns, so it is opt-in per instance and belongs at the top or the bottom of a page — interrupting both columns mid-page makes the reader find their place twice.

Table 1 — Characters per line for an 82mm column, by base size. The floor is 45: 11pt and 10.5pt both fall short, 10pt clears it by two, and the template still drops one step further, to 9.5pt, for headroom rather than a bare pass.
Base size	11pt	10.5pt	10pt	9.5pt	9pt
Characters	42	44	47	49	52
Conformant	no	no	yes	yes	yes

What the template forbids

Sidenotes have nowhere to go: there is no margin left. They become footnotes or endnotes, and an implementation should degrade them visibly rather than positioning them off the page — as this one does:

The claim is set out at length elsewhere.In two columns this sidenote degrades to an inline aside rather than being positioned off the page and lost.

A three-line drop cap at 3.05em is 29pt — 10mm of the column given to one letter. So the cap is neutralised here and the opening words carry the signal in small caps instead, as this paragraph does.

Set in EB Garamond, 9.5 on 13.3 points, two columns of 82mm with a 6mm gutter. Composed in HTML, printed from the browser.