Fullwidth Latin Capital Letter M

It is the grid-sized form of ordinary capital M. Fullwidth and halfwidth forms grew out of East Asian computer text: many East Asian characters occupied two display cells, while Roman letters occupied one. A wide Latin form let Roman text align to the same cell grid. Ｍ keeps M’s letter value but has a distinct width and text identity.

The Japanese standards trail starts with JIS X 0201 (1969), a character-code standard whose Roman set supplied the narrow forms. JIS C 6226 (1978), later called JIS X 0208, defined a broader Japanese character repertoire. The Shift_JIS encoding combined the sets; Unicode retained both widths so older mixed-width text could be converted without losing which form it used.

Should I use fullwidth M instead of M?

Use ordinary M unless a fullwidth field or grid requires Ｍ. In regular Latin prose, identifiers, URLs, email addresses, and many form fields, Ｍ is a different text character even though readers recognize the same letter. It fits older East Asian text, a zenkaku input mode, or deliberate alignment to a fullwidth grid.

Width is a data distinction too. The same width system appears in Chinese and Korean text; software may reject Ｍ when a field expects ASCII. Unicode compatibility normalization can change it to M, but that erases the width distinction.

How do I type fullwidth M?

Use your Japanese IME’s Full-width Alphanumeric mode. As of 2026, Microsoft Japanese IME assigns F9 to Full-width Alphanumeric and F10 to Half-width Alphanumeric. Its Japanese keyboard modes also offer the Hankaku/Zenkaku key and Shift + NonConvert; shortcuts vary by IME.

Fonts draw Ｍ differently, so its apparent proportions and spacing can vary even though the character itself is unchanged.