I’ve always thought it’s hard to find statistical information regarding software localization, so I decided to gather some of them in one place. Here are some data that I collected over time regarding localized text. I hope you may find them useful.

These are for English and are referring to application strings, so it does not apply for documentation or marketing materials:

  • Average words/string: 3.6 words
  • Average characters/string: 22 characters
  • Most characters/strings: <1000

Text size expansion when translated

These data were published by IBM, in their National Language Design Guide Volume 1:

Characters in English Average expansion
<10 200-300%
11-20 180-200%
21-30 160-280%
31-50 140-160%
51-70 130-140%
Over 70 150%

You may find this very useful for UI strings because it allows you to do pseudo-localization with strings length expanding, in order to evaluate how your interface will behave.

I encountered the biggest expansions on Russian language, followed by French. If you rely on word-wrap, remember, that there are languages with very long strings, German being one of them.

Translation metrics

  • IT/documentation - ~2000-2500 words/day (considering 8h workday)
  • Law/licensing – 50% speed decrease
  • On easy text you can boost the productivity a lot, reaching even 5000 words/day.