Full and Half Width Converter

📖 Tool Introduction

Convert the characters in a piece of text between their full width and half width forms, with the result appearing as soon as you paste.

A full width character takes two character cells and a half width one takes a single cell. Typing English letters, digits or punctuation with a Chinese input method tends to produce the full width versions, so you end up with things that look correct but are not the characters the rest of the system expects. That difference matters more than it looks: a full width comma or digit is a different code point from the ASCII one, so comparisons fail, validation rejects the value and searches miss a record that is plainly there. It is one of the most common causes of a form that refuses to accept an entry which looks perfectly normal.

The full width forms occupy one continuous block in Unicode and map onto ASCII by a fixed offset, so the conversion is a per character mapping rather than a set of replacements. Nothing is guessed and nothing can come out mangled. The ideographic space is a single exception outside that block and is handled on its own, since it is the space used in Chinese typesetting and is what people usually mean when they ask for a full width space.

In practice the tool gets used for a few recurring jobs: normalising text copied out of a word processor or a web page, cleaning full width digits out of user input before it reaches a database, and converting the punctuation in a block of Chinese text to half width so that it can go into code or onto a command line. Running it the other way is useful too, when a block of mixed text needs to line up in a Chinese layout.

The result comes with the total character count and the number of characters that actually changed, which tells you at a glance whether the conversion touched what you expected. Everything runs in the browser, so the text you paste never leaves your device.

✨ Key Features

• Full to half: normalise letters, digits and punctuation in one pass
• Half to full: for Chinese typesetting that needs aligned widths
• The ideographic and ASCII spaces map to each other rather than being dropped
• Per character mapping rather than pattern replacement, so nothing is mangled
• Shows the total characters and how many actually changed
• Runs locally: your text is never uploaded

🚀 How to Use

1. Paste or type the text you want converted on the left
2. Pick the direction on the right: full to half, or half to full
3. Press process, or use Ctrl plus Enter
4. The result box shows the converted text and the count of changed characters
5. Copy result puts it on your clipboard

⚠️ Things to Note

• Data source: Built on the fixed Unicode mapping between the full width block and ASCII, applied character by character
• Chinese characters are untouched: Han characters have no full or half width variant, so only letters, digits, punctuation and spaces change
• Use half width for code: Programming languages, config files and command lines expect half width punctuation and digits; full width ones are syntax errors
• Full width suits typesetting: Chinese layouts sometimes want full width punctuation for alignment, and then the reverse conversion is the right direction
• Privacy: Everything runs in the browser. The text you paste is never sent to a server