Typography is not merely aesthetic—it is a performance variable. Research in readability and cognitive ergonomics consistently shows that font selection and line spacing significantly affect how quickly and accurately readers process text. For language service providers delivering technical, medical, and regulatory documents, these are not academic details. They directly affect whether users can safely and efficiently consume localized content.
Studies on reading speed demonstrate that optimized line spacing—typically 1.2 to 1.5 times the font size—can improve reading pace by up to 20 percent compared to cramped layouts. Similarly, appropriate font choices for body text reduce eye strain and comprehension errors. Sans-serif fonts often perform well on screen; serif fonts remain strong for long print documents. The wrong choice in a localized manual is not a style issue—it is a usability failure.
These effects multiply across languages. A font that works for English may lack glyphs for Polish diacritics, Czech characters, or Vietnamese tone marks. Line spacing that accommodates English may still overflow when applied to expanded German translations. Locale-appropriate typography must be planned during template design, not improvised during post-translation DTP.
For LSPs, the practical application is straightforward. Include typography review in your DTP QA checklist. Verify font coverage for every target script. Test line spacing with longest-language samples before finalizing templates. When clients provide restrictive brand fonts with poor Unicode coverage, flag the risk and recommend alternatives early.
Layout facts like the 20 percent reading speed difference transform typography from a design preference into a project requirement. Deliver documents that respect these principles, and your localized content will not only be accurate—it will be genuinely usable for the readers who depend on it.