Full-width / Half-width Converter

How to use the Full-width / Half-width Converter

Type or paste the text you want to convert into the text area above. The result updates in real time based on the selected conversion direction and the checked character categories. For example, with "Full-width → Half-width" selected, pasting ＡＢＣ１２３ instantly converts it to ABC123.

1. Choose a direction: Use the segment buttons to switch between "Full-width → Half-width" and "Half-width → Full-width".
2. Select categories: Use the checkboxes to limit conversion to specific character types — Alphanumerics, Symbols, Spaces, and/or Katakana.
3. Enter your text: Type or paste text into the input area and the converted result appears the moment you paste. The "Examples (click to try)" chips above the input field load realistic mixed-text samples instantly.
4. Copy the result: Click the "Copy" button to copy the converted text to your clipboard.

What are full-width and half-width characters?

In Japanese text, the same letters, digits and symbols exist in two widths. Full-width forms (ＡＢＣ１２３) take up the space of one Japanese character and line up neatly with kanji and kana; half-width forms (ABC123) are the ordinary ASCII width. Katakana has a half-width form too (ｱｲｳ). Both exist because Japanese computers fit Latin letters into the same square grid as kanji. Mixing widths is common when data is typed by different people or pasted from different systems, and it quietly breaks searching, matching and sorting — so normalizing everything to one width keeps a list consistent. That clean-up is what this tool is for.

Common use cases

• Normalizing inconsistent character widths in address books and contact lists (e.g., converting full-width alphanumerics to half-width)
• Standardizing character types in system input forms
• Converting half-width katakana mixed into data to consistent full-width katakana
• Data cleaning for CSV files and spreadsheets

Frequently Asked Questions