Guides JP

Fullwidth Halfwidth Converter Tool

Convert between fullwidth and halfwidth characters.

Last updated: 2026/10/16 Text Feedback & bug reports
Input
Settings

Converts halfwidth letters, numbers, katakana, symbols, and spaces to fullwidth.

How to Use

1

Enter Text

Type or paste the text you want to convert.

2

Select Direction and Target

Choose "Halfwidth → Fullwidth" or "Fullwidth → Halfwidth" and select character types.

3

Convert

Click the "Convert" button to see the result.

About Fullwidth/Halfwidth

Halfwidth characters are single-byte, while fullwidth characters are double-byte. In Japanese computing, letters, numbers, and katakana exist in both forms.

Need to swap between hiragana and katakana instead of width? Use the Kana Converter. To change letter casing such as UPPER/lower, try the Case Converter, and if pasted text shows garbled characters, the Mojibake Fixer can help restore it before converting widths.

Features

  • Bidirectional ConversionConvert both halfwidth to fullwidth and fullwidth to halfwidth.
  • Character SelectionSelect letters, numbers, katakana, symbols, and spaces individually.
  • One-click ConversionConvert all at once with a single button click.
  • Privacy ProtectedAll processing happens in your browser. Data is never sent to servers.

Use Cases

  • Standardizing data entry
  • Normalizing form input values
  • Formatting CSV data
  • Consistent document formatting
  • Converting strings for programming

FAQ

Is the converter free?
Yes, it is completely free. No registration required.
Which characters are converted?
Letters (A-Z, a-z), numbers (0-9), katakana, common symbols, and spaces.
Are kanji and hiragana converted?
No, kanji and hiragana do not have halfwidth forms.
Is my text saved?
No, all processing happens locally in your browser.
Can it handle long texts?
Yes, within browser memory limits.
How can I convert only between half-width and full-width katakana?
Check only "Katakana" under Target Characters, or use the "Half Kana to Full Kana" / "Full Kana to Half Kana" quick-convert buttons. Letters and symbols stay untouched while only katakana is converted. Half-width katakana with dakuten/handakuten (such as ｶﾞ or ﾊﾟ) are correctly combined into (or split from) a single full-width character. To swap between hiragana and katakana, use the Kana Converter as well.
How do I switch the conversion direction?
Just choose "Halfwidth to Fullwidth" or "Fullwidth to Halfwidth" under Direction. A short description updates with your choice so the conversion direction is always clear. Common combinations can be run in one click from the Quick Convert buttons.

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