What does the halfwidth converter do?

It maps fullwidth Unicode characters back to their narrow halfwidth equivalents. Fullwidth Latin letters and digits become standard ASCII, and fullwidth Katakana becomes halfwidth Katakana in the U+FF61 to U+FF9F block.

How does the Latin conversion work?

Fullwidth Latin forms occupy U+FF01 to U+FF5E, exactly 0xFEE0 above their ASCII counterparts, so the tool subtracts 0xFEE0. The ideographic space U+3000 is mapped back to a normal space.

Does it handle Japanese Katakana?

Yes. Fullwidth Katakana characters are mapped to halfwidth Katakana where an equivalent exists, including handling for the dakuten and handakuten voicing marks where appropriate.

Why would I normalise to halfwidth?

Halfwidth normalisation is common when cleaning data for databases, search indexing or forms, where mixed fullwidth and halfwidth characters can cause duplicate or mismatched entries.

No. All conversion runs in your browser with JavaScript, so the text you paste never leaves your device.

Halfwidth Katakana Converter

The halfwidth converter reverses the widening that produces fullwidth or “aesthetic” text and also narrows fullwidth Japanese Katakana into its compact halfwidth form. It is useful both for undoing decorative wide text and for normalising data so that fullwidth and halfwidth versions of the same characters do not create mismatches.

How it works

Fullwidth Latin letters, digits, and punctuation live in the Unicode block U+FF01 to U+FF5E, exactly 0xFEE0 (65248) code points above the matching printable ASCII characters. The tool subtracts 0xFEE0 from any character in that range to recover the ASCII original, and converts the ideographic space U+3000 back to an ordinary space. For Japanese, fullwidth Katakana in the U+30A0 block is mapped to halfwidth Katakana in the U+FF61 to U+FF9F block using a lookup table; voiced characters that have no single halfwidth glyph are written as a base character followed by the halfwidth voicing mark.

Example

Fullwidth Ｇｅｒａ is converted character by character — Ｇ (U+FF27) minus 0xFEE0 gives G (U+0047) — producing Gera. Fullwidth Katakana such as カ becomes the halfwidth ｶ. To go the other way and widen narrow text, use the fullwidth converter.