Full-width / Half-width Converter
Enter text and it will be converted between full-width and half-width for the character types you select (alphanumerics, symbols, katakana, and spaces). Useful for normalizing inconsistent form input or data that mixes in half-width katakana. To check the character count of the result, try the Character Counter as well.
🔒 Runs in your browser · Your data is never sent to a server
Notes
- You can convert alphanumerics, symbols, katakana and spaces. Hiragana and kanji are not converted.
- Half-width katakana with dakuten is two characters (for example "ｶﾞ"), so the character count decreases when converting to full-width and increases when converting to half-width.
- Only the selected character types are converted. Types you deselect are left as they are.
Glossary
Full-width / half-width
Full-width characters occupy a square cell (the standard width used for Japanese text), while half-width characters occupy half that width. Even the same letter, such as "Ａ" (full-width) and "A" (half-width), is treated as a different character by computers, which can affect search results or program behavior.
Half-width katakana
Katakana rendered at half width, as defined by JIS X 0201. Voiced and semi-voiced marks ("ﾞ" and "ﾟ") are separate characters, so converting to full-width combines each mark with the preceding character into a single full-width katakana character.
FAQ
Which character types can be converted?
You can choose among alphanumerics, symbols, katakana and spaces, converting between full-width and half-width. Hiragana and kanji are not affected.
How are half-width katakana with dakuten handled?
Half-width "ｶﾞ" (two characters) is merged into full-width "ガ" (one character), and the reverse conversion produces two characters, so the length changes.
How can I use it to standardize form input?
Normalizing phone numbers, postal codes and emails to half-width makes searching and duplicate checks easier. Use the character counter to check the resulting length.
Share this page