Spacing and Measure

Measure is the length of a line of text, traditionally stated in picas and now usually counted in characters. Word spacing is the amount of space between words within that line. The two are inseparable because they jointly determine what happens at the end of every line, where the reader's eye must travel back and drop exactly one line down. Too long a measure and the eye loses the return, causing doubled or skipped lines. Too short and the reading is broken into fragments, with hyphenation and ragged spacing becoming unavoidable. Robert Bringhurst gives a widely cited range of forty-five to seventy-five characters per line for single-column text, with sixty-six as a satisfactory average.

Measure exists as a concern because reading is not a smooth glide. The eye moves in short jumps called saccades, fixing briefly on clusters of letters and then leaping forward, and at the end of a line it performs a much longer return sweep to the start of the next. That return sweep is the fragile moment: it must land on the correct line, and its accuracy decreases as the distance increases. Word spacing matters for a related reason. Spaces are what let the eye chunk a line into words rather than a continuous string, and spacing that is inconsistent — the classic rivers of white running down a badly justified column — disrupts the chunking and slows reading measurably.

• →A paperback novel, set at roughly sixty to seventy characters per line, which is why paperbacks are the width they are.
• →A broadsheet newspaper, which solves a wide page by splitting it into narrow columns rather than running one enormous measure.
• →A website with a content column capped around seventy characters while the page itself remains full width.
• →A justified column with large gaps and visible rivers, the usual symptom of too short a measure for the justification method.

Measure was originally a physical quantity. A compositor set type into a stick adjusted to a fixed width, and the line had to be filled exactly, so every line was justified by hand using metal and brass spaces of different thicknesses. Getting even spacing was a genuine craft skill, and a good compositor also adjusted word spaces subtly across several lines to avoid rivers. The Linotype machine automated line-filling from the 1880s but inherited the same requirement. Jan Tschichold's Penguin Composition Rules, written after he was appointed to overhaul Penguin Books in 1947, are a compact statement of this inherited discipline, specifying such details as how word spacing should be handled and when hyphenation is acceptable.

On the web, measure became a variable rather than a setting, because the same text can appear at any window width. Designers therefore constrain it, commonly by setting a maximum width on the text container in units tied to the typeface rather than the viewport. CSS provides justification and hyphenation controls, but browser justification is still cruder than a good print engine, so setting long text ragged right is often the safer choice. The deeper change is that word spacing is now largely out of the designer's hands: the browser or operating system applies the font's built-in space width and its own justification algorithm. What remains firmly in the designer's control is measure, which is the more powerful of the two.

Open any well-designed long-form article on a phone and then on a wide desktop monitor. The text column stays roughly the same width on both; on the desktop, the extra space becomes margin rather than longer lines. This is a deliberate refusal of the available width, and it is the single most common reason one article feels effortless to read and another, with identical content, feels exhausting. The tell is easy to spot on a badly set page: reading a line, arriving at the right edge, and then having to hunt for where the next one begins. That hunt happens on every line, and it is entirely a measure problem.

• →Aim for roughly forty-five to seventy-five characters per line for continuous text.
• →As measure grows, leading must grow with it, or the return sweep fails.
• →Constrain the text column independently of the page or viewport width.
• →Ragged right is usually safer than justification when hyphenation control is poor.
• →Even word spacing matters more than perfectly aligned right edges.
• →Narrow measures need tighter word spacing and active hyphenation to avoid rivers.