Full-width / Half-width Converter
Convert full-width and half-width alnum, symbols, and katakana directly in your browser.
Use category toggles, change preview, URL/code protection, and settings sharing without sending text anywhere.
How to use
- Paste your text into the input field.
- Choose the direction and a preset.
- Adjust categories and advanced settings if needed.
- Review the converted result and copy or download it.
Examples
Normalize form input to half-width
Input: Ｆｉｎｉｔｅ Ｆｉｅｌｄ！ ２０２６／０３／１２
Output: Finite Field! 2026/03/12
Convert half-width katakana to full-width
Input: ﾌｧｲﾅｲﾄﾌｨｰﾙﾄﾞ
Output: ファイナイトフィールド
Convert voiced katakana to half-width
Input: ガッツポーズ
Output: ｶﾞｯﾂﾎﾟｰｽﾞ
FAQ
Is my text sent anywhere?
No. Conversion runs entirely in your browser.
Can I convert only alnum or only katakana?
Yes. Each category can be turned on or off independently.
Is this the same as Unicode normalization?
No. This tool focuses on width conversion only and avoids ambiguous compatibility conversions by default.
Does it convert hiragana or kanji too?
No. Version 1 only targets alnum, symbols, katakana, and optional spaces.
Will it convert URLs or code snippets?
Not by default. URLs, email addresses, and code are protected unless you turn that off.
Why are some katakana left unchanged?
Some characters such as `ヷ` or `ヵ` do not have a strict half-width counterpart, so the tool leaves them unchanged for safety.
Can I share only settings?
Yes. The share link stores settings only and never includes your text.
Glossary
Full-width
A wider character form commonly used in Japanese text environments, such as `Ａ`, `１`, and `！`.
Half-width
A narrower character form used by ASCII and half-width katakana, such as `A`, `1`, `!`, and `ｶ`.
Half-width katakana
Katakana written in half-width form, such as `ｶ`, `ﾀ`, and `ﾅ`. Voiced sounds may use two characters, like `ｶﾞ`.
Dakuten / handakuten
Marks such as `ﾞ`, `ﾟ`, `゛`, and `゜` that change the sound of kana.
Notes
- Characters such as `〜`, `￥`, compatibility ideographs, and circled numbers are outside the scope of simple width conversion and are left unchanged.
- If the destination system has strict character rules, review the result before submitting it.
- Only disable URL/code protection when you intentionally want to convert those segments too.