Full-width / Half-width Converter

What is the difference between zenkaku and hankaku?

Zenkaku (全角, "full width") characters take up a full square of space, the width used by Japanese kanji and kana; hankaku (半角, "half width") characters take up half that space, closer to normal Latin-alphabet typing. The same letter, digit or katakana can typically be written in either width, and many Japanese forms and systems require one or the other.

This tool converts letters (A-Z, a-z), digits (0-9), common symbols, and katakana (including voiced sounds like ガ and パ) between the two widths, so text pasted from one system can be reformatted to match another's input rules.

How do I convert full-width (zenkaku) text to half-width (hankaku)?

Map each full-width letter, digit and symbol (U+FF01-FF5E) to its half-width ASCII equivalent by subtracting a fixed Unicode offset (0xFEE0), map the ideographic space to a normal space, and decompose voiced full-width katakana into a half-width kana plus a separate half-width sound mark. Example: full-width "Ａ１！" becomes half-width "A1!", and full-width "ガ" becomes half-width "ｶ" + "ﾞ".

Steps for full-width to half-width conversion

1. For letters, digits and common symbols in the full-width block (！ through ～), subtract 0xFEE0 from the character code to get the half-width ASCII character.
2. Replace the full-width ideographic space (　) with a normal half-width space.
3. For a voiced full-width katakana like ガ, ジ, ブ, or a semi-voiced one like パ, split it into its unvoiced half-width base (ｶ, ｼ, ﾌ, ﾊ) followed by a half-width voicing mark (ﾞ) or semi-voicing mark (ﾟ).
4. For a plain full-width katakana (ア through ン, plus small kana like ァ and ッ), look up its single-character half-width equivalent from the JIS X 0201 half-width katakana table.
5. Leave kanji, hiragana, and any character without a half-width form unchanged.

The conversion rule

• Zenkaku (全角) = full-width, one full square of monospace width
• Hankaku (半角) = half-width, half that width
• Dakuten (゛) = voicing mark, e.g. turns ｶ (ka) into ガ (ga); Handakuten (゜) = semi-voicing mark, e.g. turns ﾊ (ha) into パ (pa)

Example conversions

Frequently asked questions

Why does a full-width voiced katakana like ガ become two half-width characters?

The half-width katakana set (JIS X 0201) has no single character for voiced sounds — instead it represents ガ as the base character ｶ followed by a separate half-width voicing mark ﾞ. Converting back combines that pair into the single full-width ガ.

Does this tool convert kanji or hiragana to half-width?

No. Kanji and hiragana have no half-width forms in standard Japanese encoding, so this tool leaves them unchanged in both directions — only Latin letters, digits, common symbols, and katakana have both a full-width and half-width version.

Why do some Japanese forms require half-width input?

Many legacy Japanese systems (banking, government forms, postal codes, phone numbers) were built around half-width digits and letters for consistent field widths, so they reject or mis-parse full-width input even though it looks identical to a human reader.

Is converting to half-width and back guaranteed to give the same text?

Yes, for the characters this tool covers (Latin letters, digits, common symbols, katakana including voiced sounds) the conversion is fully reversible in both directions, since every full-width character maps to exactly one half-width representation and back.

This tool converts Latin letters, digits, common ASCII symbols, and katakana (including voiced and semi-voiced sounds) between full-width and half-width; kanji, hiragana, and characters outside these sets are left unchanged since they have no half-width equivalent.