Translate a Flutter App into Simplified Chinese

What changes in an .arb file when the target is Chinese

A Flutter app localised with flutter gen-l10n keeps its strings in .arb files: app_en.arb (or whichever source language you write in) and app_zh.arb for the target. Moving to Simplified Chinese affects things a European language never does.

• Punctuation becomes full-width. "Hello, {name}!" becomes "你好，{name}！": Chinese comma and exclamation mark. Colons become ： and full stops 。.
• There are no spaces between words. "{count} files selected" becomes "已选择 {count} 个文件": the word order changes and a measure word, 个, sits between the number and the noun.
• Only one plural form. CLDR rules for Chinese have a single category, other; nouns do not change with quantity.

The text uses two to three times fewer characters, but each character is wider than a Latin letter, so the space taken on screen changes little. A button that is too narrow in English will often still be too narrow in Chinese, while a very short label may look lost in a button sized for the source.

Plurals, select and measure words

An ICU message such as {count, plural, =0{No messages} =1{One message} other{{count} messages}} becomes {count, plural, =0{没有消息} other{{count} 条消息}} in Chinese. Manuce checks the message structure and makes sure the other category, the only one Chinese uses, is present: it is the case flutter gen-l10n requires. Exact cases such as =0 can stay where a dedicated wording reads better.

The real trap lies elsewhere: the measure word depends on what is being counted. Messages take 条消息, photos 张照片, files 个文件, contacts 位联系人. A key called itemCount with no description does not say what is counted, so the description in @itemCount matters.

For gender select messages, written Chinese distinguishes 他 (he) from 她 (she), although both sound the same. The other branch gets a neutral form suited to the context, for instance 对方 ("the other person") in a chat app.

What Manuce returns, and what it does not do

• The same file in the same format: indentation, key order, quotes, line endings, encoding and BOM preserved. Only the values change.
• @ metadata keys are not translated; their descriptions are used as context. @@locale is switched to the target language.
• Every translated value is compared with the source: if a placeholder such as {count} or {name} is missing or altered and the discrepancy persists, the source value is kept and the report says so.
• Not translated: keys, empty values, URLs, email addresses, numbers, colours, date formats, identifiers, and anything you mark as non-translatable.
• Pricing is based on the words in the values, keys and tags excluded; Chinese carries a ×1.6 coefficient on the per-word rate.

Manuce does not edit your pubspec.yaml, your supportedLocales or your fonts, and does not test the display on a device. Traditional Chinese (Taiwan, Hong Kong) is a separate language and needs its own file; the multi-language discount applies from two languages. Manuce does not produce sworn or certified translations either, so terms that must be certified need a qualified translator.

Preparing the source file

• Describe ambiguous keys. "@send": {"description": "Button: send a chat message"} points to 发送 rather than a verb for posting a parcel. For one-word labels like "Read" or "OK", the description makes all the difference.
• Remove string concatenation in Dart. Code like 'Hello ' + name breaks in Chinese, where word order changes. Use a placeholder in the .arb instead: "greeting": "Hello, {name}".
• Flag brand names and terms that must stay in Latin script, so they are marked non-translatable.
• Leave dates to intl. Date formats are not translated: with the zh locale, DateFormat.yMMMd already outputs 2024年5月3日. Do not hard-code "3 May" in a value.
• Save the file as UTF-8, the encoding Flutter expects for .arb files; it will be kept as is.

Checks after delivery

1. Save the returned file as app_zh.arb in your translations folder, confirm that @@locale reads zh, then run flutter gen-l10n again.
2. Add Locale('zh') to your supported locales and, for iOS, declare zh among the localisations in Info.plist.
3. Fonts: a Latin-only font bundled through pubspec.yaml has no Chinese glyphs, so Flutter falls back to the system font. Check the result, and if you bundle a Chinese font, bear its file size in mind.
4. Glyph shapes: without a precise locale, some characters may render in their Japanese variants. Setting Locale.fromSubtags(languageCode: 'zh', scriptCode: 'Hans') avoids this.
5. Layout: Chinese can wrap between any two characters; check maxLines, ellipses and line height, as ideographs are taller than Latin lowercase.
6. Read the report: every string left in the source language is listed with its reason.

In practice

1. Upload your source .arb file: the quote appears at once, based on the words in the values.
2. Choose Simplified Chinese and a level, then read the free one-paragraph sample.
3. Pay and download the translated file and its report from your account within minutes.
4. Save it as app_zh.arb, run flutter gen-l10n and check fonts and layout on a device.