Skip to main content
UI Guides

Search rules

Search all UI Guides rules by name, category, or source

contentRauno

Font Subsetting

SHOULD

SHOULD: Subset webfonts to the alphabets/languages actually used and declare `unicode-range` — full font files ship glyphs you never render.

Subset fonts based on content, alphabet, or relevant languages to reduce file size

@font-face { font-family: Inter; src: url(/inter-latin.woff2) format("woff2"); unicode-range: U+0000-00FF; }

Bad

Good

Why it matters

Full font files include glyphs for many languages and scripts you may not need. Subsetting to only the character ranges used on your site can reduce font file sizes by 80-90%, improving load times significantly. Subset into the right container while you are at it: serve `.woff2` on the web and never ship a raw `.ttf` or `.otf`, which carry no web compression and land roughly 30-50% heavier for exactly the same glyphs (jakubkrehel's choosing-fonts calls them "Desktop only unless there is no other option"; `.woff` is a fallback for very old browsers, nothing more).

References

Built by Gleb Stroganov, design engineer at Evil Martians.

The rules come from other people's skills and guidelines — Vercel, Rauno Freiberg, @Ibelick, impeccable, Emil Kowalski, Tailwind, RAMS — each one credited on the Sources page. The work here is extraction and wiring: every rule is pulled into one corpus, given a good and a bad example you can operate, a MUST/SHOULD/NEVER rule an agent can paste, and a link back to where it came from.