Punctuation Converter

⚡ Runs locally🔒 No uploads🆓 Free, no sign-up

Chinese and English use two mutually incompatible punctuation systems. Chinese punctuation is full-width — ，。；：？！“” — each mark occupies the width of one Chinese character and lives mainly in the Unicode full-width block (U+FF00–U+FFEF) and the CJK symbols block (U+3000–U+303F). English punctuation is half-width ASCII — ,.;:?!"" — half the width, from the basic ASCII range. The glyphs look alike but the code points are completely different, so to a computer they are unrelated characters. That is why a Chinese document translated from English so often ends up with stray half-width commas hiding among full-width text: easy to miss when skimming, obvious in print, and fatal for exact-match search or string comparison.

There are three typical scenarios. First, translation cleanup: drafts produced by human translators or AI translation frequently retain English half-width punctuation, and fixing them one by one is slow and error-prone — paste the text here and convert everything in one click. Second, writing consistency: articles, papers, and product docs usually require full-width punctuation, and writers switching between Chinese and English input methods inevitably mix the two; one conversion unifies the whole document. Third, data cleaning: copying phone numbers, prices, or model numbers from Chinese web pages into English-language systems like Excel or a CRM breaks lookups and formulas when full-width punctuation sneaks in — convert to half-width first, then paste.

A few edge cases deserve a clear explanation up front. First, auto-detection looks only at punctuation: if a passage mixes Chinese and English punctuation, it converts Chinese to English; for heavily mixed text, pick the direction manually or convert in sections. Second, English quotes converting to Chinese are paired as open and close in order of appearance (1st, 3rd, 5th become left quotes), while apostrophes inside contractions such as don't and it's are detected and preserved; a leftover unpaired quote is treated as an opening quote. Third, the comma is ambiguous in reverse: an English half-width comma always becomes the Chinese comma (，), never the enumeration comma (、) — no program can tell enumeration from pausing, so fix those by hand. Fourth, hyphens and periods stay half-width in English-to-Chinese conversion: Chinese has no full-width counterpart for the period (it uses 。 instead), so keeping - and . untouched inside dates and version numbers is the sane behavior. Fifth, the full-width space is not converted by default; tick the checkbox when your layout needs it.

All conversion happens locally in your browser — your text is never uploaded to any server, so content containing sensitive information is safe to paste. The tool reports exactly how many punctuation marks were converted, and auto-detection announces which direction it chose, so the whole process is transparent and verifiable.