Full-Width ⇄ Half-Width Converter

Japanese, Chinese and Korean computers can type Latin letters, digits and symbols in two widths. Full-width characters (ＡＢＣ１２３) are as wide as a Chinese character; half-width ones (ABC123) are the normal characters used everywhere else. They look similar, but to software they are completely different, which causes many everyday problems. This tool converts between the two.

Why full-width characters cause trouble

A phone number typed as ０３－１２３４－５６７８ fails form validation, an email address with a full-width ＠ is rejected, a spreadsheet treats full-width digits as text so sums come out as zero, and a database search for “ABC” does not find “ＡＢＣ”. Converting to half-width before submitting or importing data fixes all of these. The counter below the result shows how many full-width characters the input contained.

What is converted

Letters, digits and symbols in the full-width ASCII block are mapped to their ordinary equivalents, and the ideographic space (a full-width blank) becomes a normal space. Each group has its own switch, so you can, for example, convert letters and digits but keep ideographic spaces for Japanese layout. Hiragana and kanji have only one width and are never changed.

Half-width katakana

Older systems such as cash registers, bank transfers, legacy databases and some SMS formats use half-width katakana (ｶﾀｶﾅ), where voiced sounds are written as two characters: ｶ plus the mark ﾞ for ガ. Converting to full-width combines each pair into a single standard character, so ｶﾞ becomes ガ, ﾊﾟ becomes パ and ｳﾞ becomes ヴ, and converts half-width punctuation such as ｡ and ｢ ｣ as well. The reverse direction splits voiced kana back into base and mark for systems that require half-width input.

Why not just normalise the text?

Unicode’s NFKC normalization also turns full-width letters into normal ones, but it changes many other characters at the same time: ligatures like fi, superscripts like ², circled numbers and Roman numeral characters. This tool changes width only, so the rest of your text stays exactly as it was.

Going the other way

Converting to full-width is useful for Japanese layouts that require it, such as vertical text, and for the “vaporwave” aesthetic, where ＷＩＤＥ　ＴＥＸＴ is a style in itself.

Files and privacy

Open a .txt or .csv file to convert it whole, and download the result. Everything runs in your browser, so customer lists and addresses are not uploaded.

A worked example

A customer typed ＴＥＬ：０３－１２３４－５６７８ and ｅｍａｉｌ＠ｅｘａｍｐｌｅ．ｃｏｍ into a form, and the system rejected both. Converted to half-width, they become TEL:03-1234-5678 and [email protected], which pass validation. The counter shows how many full-width characters were found. In the other direction, an old bank file containing ﾀﾅｶ ﾀﾛｳ converts to タナカ タロウ, and voiced kana such as ﾀﾞ are combined into ダ instead of being left as two characters.

Width in CSV and spreadsheet data

Customer lists exported from Japanese, Chinese or Korean systems often mix widths in the same column, so de-duplication and sorting fail. Convert the whole file to half-width first, then remove duplicates or sort; the counts in the panel show how many characters were affected.

Related tools

Write Japanese with a Latin keyboard using Romaji to Kana, convert Arabic or Indian digits with the Arabic Numerals Converter, or clean spacing and invisible characters with the Text Cleaner.