Omikuji Tools Text & Dev

Full-width ⇔ Half-width Converter

Convert letters, digits, symbols, katakana and spaces between full-width and half-width forms, choosing which types to change. Hiragana ⇔ katakana included.

✨ Features

  • Tick letters, digits, symbols, katakana and spaces individually and convert only what you need
  • Half-width katakana voicing marks are merged on the way to full-width and split on the way back
  • Hiragana ⇔ katakana conversion at the same time
  • Converts as you type; shows how many characters changed; copy, feed the result back as input, or share a URL

🪄 Use cases

Form validation errors

Fix phone, postal and card numbers that must be half-width digits.

Consistent addresses and names

Normalize house numbers in a list to one width.

Excel / CSV cleanup

Make product codes half-width so lookups match.

Legacy half-width katakana

Turn ｶﾀｶﾅ from old systems into カタカナ.

🔒 Privacy

Text is processed in your browser and never sent to a server. Only when you shorten a share URL is that URL (including the text) sent to the shortening service.

❓ FAQ

What are full-width and half-width characters?

Full-width characters (ＡＢＣ, １２３, アイウ) take the same width as a Japanese character; half-width ones (ABC, 123, ｱｲｳ) take half. They look alike but are different code points, so searches and comparisons do not match.

Are kanji and hiragana converted?

They have no half-width form and are left unchanged. Hiragana can only be converted to (full-width) katakana.

Which symbols are covered?

ASCII punctuation and its full-width forms. Full-width dashes become "-" and the full-width yen sign becomes a backslash.

What happens to voicing marks in half-width katakana?

ｶﾞ becomes ガ (one character) when going to full-width, and ガ becomes ｶﾞ (two characters) when going to half-width.

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Direction
Apply to

Half-width katakana voicing marks (ｶﾞ, ﾊﾟ) are merged into one character when converting to full-width. Full-width minus and hyphen both become "-".