Text Expansion Calculator

Estimate how much longer your UI text gets after translation into German, French, Finnish, Japanese and other languages.

Source length
12
Reserve in UI
24

Pick the languages you plan to support.

LanguageTypical changeExpected charactersShort string ruleReserve
German de+10% to +35%13 to 1622 to 2424
French fr+15% to +20%14 to 1422 to 2424
Spanish es+15% to +25%14 to 1522 to 2424
Italian it+10% to +25%13 to 1522 to 2424
Portuguese pt+15% to +30%14 to 1622 to 2424
Polish pl+20% to +30%14 to 1622 to 2424
Russian ru+15% to +30%14 to 1622 to 2424
Finnish fi+25% to +40%15 to 1722 to 2424
Japanese ja-55% to -10%5 to 115 to 1111
Chinese zh-50% to -20%6 to 106 to 1010

Runs in your browser. Files are not uploaded unless the tool says otherwise.

Why translated text gets longer

English is a compact language. The same sentence in German, French or Finnish typically needs 15 to 35 percent more characters, and single words can double: "Settings" becomes "Einstellungen", "Save" becomes "Enregistrer". Chinese, Japanese and Korean go the other way and often need fewer characters, but each character is wider and taller, so the rendered width shrinks less than the character count suggests.

Where the numbers come from

The per-language ranges are the values commonly cited in localization guides, including the W3C article "Text size in translation" and IBM globalization guidelines. The short string rule is the IBM table that links expected growth to the length of the English source: strings under 10 characters can grow 100 to 200 percent, while strings over 70 characters usually grow around 30 percent. Both are averages over large corpora, so treat them as a planning aid rather than a guarantee. Your own translation memory is the best source once you have a few thousand translated strings.

How to use the reserve value

  • Size buttons, tabs, table headers and menu items for the reserve length, not for the English text.
  • Prefer layouts that wrap or grow (flexbox, auto-sizing) over fixed widths and text-overflow: ellipsis.
  • Set a character limit on keys that truly cannot grow (push notifications, SMS, hardware displays) and tell translators about it.
  • Test with a pseudo-localized build to see the overflow before the translation arrives.

Character limits in SimpleLocalize

Every translation key in SimpleLocalize can carry a character limit. Translators see it in the editor, auto-translation respects it, and the QA checks flag translations that exceed it. Read more in the QA checks documentation.

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