How to Use
Paste your text into the input area and the conversion result will appear in real-time. Choose between "Full → Half" and "Half → Full" conversion directions. Select which character categories to convert: Letters, Digits, Symbols, Katakana, Spaces, and Japanese Symbols. For example, to convert only alphanumeric characters to halfwidth while keeping katakana fullwidth, check only Letters and Digits. Converted characters are highlighted in yellow so you can see exactly what changed.
What Are Fullwidth and Halfwidth Characters?
Fullwidth and halfwidth characters differ in display width and Unicode code points. Fullwidth characters (e.g., Ａ, １, ア) match the width of Japanese fonts and are defined in the Unicode "Halfwidth and Fullwidth Forms" block (U+FF00-FFEF). Halfwidth characters (e.g., A, 1, ｱ) use standard Latin character width. Mixing fullwidth and halfwidth in data entry or CSV files can cause search and sorting issues. This tool lets you unify them with one click.
Bulk Conversion
To convert large amounts of text, paste the entire text into the input area. This tool supports up to 1,000,000 characters, and all processing happens in your browser for fast conversion even with large datasets. To convert data from Excel or spreadsheets, copy the cell contents, paste them here, then copy the converted result back. Use category selection for fine control like "only halfwidth alphanumeric" or "only fullwidth katakana".
Tips for Standardizing Character Width
The most common rule in business data is "alphanumeric in halfwidth, katakana in fullwidth." Standardizing character width is important for addresses, phone numbers, email addresses, and other data requiring accuracy. Converting data before importing into CSV files or databases prevents search and matching issues later. Use the "JP Symbols" category to control fullwidth/halfwidth conversion of punctuation (、。) and brackets (「」) independently.
FAQ
- How do I convert fullwidth to halfwidth?
- Select "Full → Half" as the conversion direction and enter your text. You can choose which character categories to convert (Letters, Digits, Symbols, Katakana, Spaces, JP Symbols) using checkboxes. The result appears in real-time with converted characters highlighted in yellow.
- How do I bulk convert fullwidth to halfwidth?
- Paste all the text you want to convert into the input area. This tool supports up to 1,000,000 characters, and all processing happens in your browser. After conversion, use the "Copy" button to copy the result to your clipboard.
- What is the difference between fullwidth and halfwidth?
- Fullwidth characters (e.g., Ａ, １, ア) are designed to match the width of Japanese fonts, while halfwidth characters (e.g., A, 1, ｱ) use standard Latin width. In Unicode, they have different code points, so fullwidth "Ａ" and halfwidth "A" are treated as different characters by computers.
- How are halfwidth katakana dakuten handled?
- Halfwidth katakana dakuten (ﾞ) and handakuten (ﾟ) exist as separate characters. During half-to-full conversion, they are correctly combined with the preceding character into a single fullwidth voiced/semi-voiced character (e.g., ﾃﾞ → デ, ﾊﾟ → パ). All 26 voiced/semi-voiced combinations are supported.