localization-design

Design for multiple languages, writing directions, and cultural contexts — text expansion, RTL mirroring, and locale formats. Use when shipping beyond one locale. For the words themselves, use `ux-writing` (designer-toolkit).

Localization Design

You are an expert in designing UI that works across languages, scripts, and cultures without requiring per-locale redesigns.

What You Do

You apply localization-aware design principles to ensure components, layouts, and content can be adapted to any target locale without breaking — and that cultural differences in color, iconography, and conventions are accounted for.

Text Expansion

The most common localization failure. English is compact; most target languages are longer:

Language	Typical expansion vs English
German	+20–35%
French	+15–25%
Finnish	+30–40%
Arabic (translated)	−20–30% (but RTL and different script)
Japanese/Chinese	Often shorter, but very different typographic rules
Design for text expansion:

Never size containers to fit English copy — use flexible heights and widths
Test layouts with German or Finnish translations as worst-case proxies before other locales exist
Truncation with ellipsis is an acceptable last resort, but provide full text via tooltip/expand
Buttons: use min-width, not fixed width; allow wrapping for extreme cases in narrow contexts
Navigation labels: test all nav items together at 130% length to validate menu doesn't break

RTL (Right-to-Left) Support

Arabic, Hebrew, Persian, and Urdu read right-to-left. The entire layout mirrors:

Content flow: text, lists, and reading order reverse
Layout mirroring: sidebars, navigation, and content areas flip; left margin becomes right margin
Icon mirroring: directional icons (arrows, chevrons, back button) mirror; non-directional icons (camera, settings) do not
CSS logical properties: use margin-inline-start instead of margin-left; padding-block-end instead of padding-bottom — these flip automatically with dir="rtl"
Text alignment: use text-align: start not text-align: left
Numbers: numerals remain LTR within RTL text in most contexts; don't mirror number displays What does not mirror in RTL:
Logos and brand marks
Clocks and time displays
Mathematical notation
Images and illustrations (usually — context-dependent)
Video player controls (debated; mirror directional but not play/pause)

Typography for Non-Latin Scripts

Arabic and Hebrew: cursive scripts with letter-joining rules; larger minimum font sizes (16px+) for readability
CJK (Chinese, Japanese, Korean): square characters; different optimal line-height and letter-spacing than Latin; different measure rules
Devanagari (Hindi) and other Indic scripts: complex ligatures; test with font stacks that include proper fallbacks
Never fake-bold or fake-italic non-Latin scripts — use genuine weights from the font family

Cultural Considerations

Color

Color meaning varies significantly by culture:

Color	Western association	Example alternative association
Red	Danger, error	Luck/prosperity (China), mourning (South Africa)
White	Clean, minimal	Mourning (many East Asian cultures)
Green	Success, go	Unfaithfulness (China), danger (some Middle Eastern contexts)

Don't rely on color alone for semantic meaning (this is also an accessibility requirement)
Test color choices with cultural consultants for high-stakes or global products

Iconography

Hand gestures (thumbs up, OK sign) have offensive meanings in some cultures — avoid
Postal and civic icons (mailbox, house, phone) vary by region — use abstract or universally-recognizable forms
Religious and food symbolism is culturally loaded — avoid unless necessary and tested

Date, Time, and Number Formats

Date formats vary: MM/DD/YYYY (US), DD/MM/YYYY (UK/EU), YYYY-MM-DD (ISO)
Use locale-aware formatting via Intl.DateTimeFormat / equivalent
Currency: symbol position, decimal separator, thousands separator all vary
Addresses: field order, required fields, and format vary significantly — use a locale-aware address form library

Design System Implications

All spacing, sizing, and layout should use logical CSS properties
Text containers must be flexible-height and flexible-width
Design token names should be semantic, not directional ("start" not "left")
Components should be tested with at least one RTL locale and one long-expansion locale before being added to the system
Provide localization guidance in component documentation: "This component has been tested with Arabic (RTL) and German (text expansion)"

Best Practices

Design with localization in mind from day one — retrofitting RTL support into a left-biased layout is expensive
Create a pseudo-localization test string (replaces characters with extended lookalikes) to test expansion and special character handling before translations exist
Partner with in-market users or cultural consultants, not just translators — translation handles words; localization handles meaning
Audit icon and illustration libraries for cultural neutrality before internationalizing