Text expansion.
Text expansion is the same content being of different lengths in different languages, and the layout having to flex accordingly.
This is the most concrete technical problem in multilingual design. German produces long, unbreakable words because of its compounding; Chinese and Japanese, by contrast, shorten markedly.
- German — expands markedly; compound words cannot be broken.
- French and Spanish — expand moderately.
- Turkish — close to English; suffixes lengthen it, but there is no compounding problem.
- Chinese and Japanese — shorten; but the character height differs.
- Arabic — moderate; the real issue is not length but direction.
The problem shows in three places in a design: headings run to more lines than expected, button labels do not fit their boxes, table columns overflow. None of the three appears in a design tested in one language.
The remedies range from the width axis of a variable font and reducing the point size to soft hyphens and boxes of flexible height. The cheapest is taken at design time: not building the layout around a fixed text length.
On this site the width axis of the typeface is narrowed for German headings, and the value was chosen by measurement — Turkish and German headings were compared at the same breakpoint and the highest value keeping them on the same number of lines was taken.
The most reliable way to test is to work with real text. A design made with placeholder text breaks when the translation arrives, and the breakage is usually noticed after publication.
A practical shortcut: machine-translate the source text into the target language and measure the length. The quality may not suffice, but the length comes out realistic and is enough for a layout test.
And a principle: text length is not a content matter but a design constraint. Asking the translator to “write it shorter” is sometimes right but usually sacrifices meaning — letting the layout flex is the better answer.
- Do not use fixed-height boxes — they overflow when the text lengthens.
- Do not assume one line — a heading can run to three lines in a third language.
- Do not use abbreviations — abbreviations differ by language.
- Test with the longest language — if it fits, the others certainly do.
- Add soft hyphens — for long compound words.
A note on measurement: testing with the longest and the shortest language is enough. Every language in between falls between those two extremes and needs no separate check — and shortening is as much a design problem as expansion.