O in Different Fonts

From an eye to a vowel

The Phoenician letter ayin meant “eye,” and the sign was a simple circle, sometimes with a dot for the pupil. In Phoenician it stood for a throat consonant that Greek didn’t have, so the Greeks reused the shape for a vowel sound: O. Later Greek split the sound into two letters, which Byzantine grammarians named o mikron (“small o”) and o mega (“big o”). Latin took only the first, and the round O has barely changed shape in nearly three thousand years.

Why O is the riskiest letter to style

A circle is a circle in any script, so O has more near-identical twins than almost any other letter:

None of these are “fonts.” They are separate characters, and swapping one in is a classic way to fake a username or web address. If you want a styled O that still counts as an O, use one of the math alphabets below. They fold back to a plain O under Unicode NFKC normalization, which some systems use to compare names.

The O styles and their quirks

Script O and the borrowed lowercase

Regular script gives you capital 𝒪 from the math block but lowercase ℴ from the much older Letterlike Symbols block. It is one of only three lowercase script letters borrowed this way (with ℯ and ℊ). In some fonts ℴ sits a touch smaller than 𝒶 or 𝓃 next to it. If that bothers you, switch to bold script 𝓞 𝓸, which is a complete, consistent set. Our cursive text generator shows both side by side.

Bubble, square and the emoji problem

Ⓞ ⓞ come from Enclosed Alphanumerics and display as plain outlined circles almost everywhere. The black square 🅾 is different: it is an emoji, so iOS, Android and Windows often draw it as a coloured button. The plain outlined square 🄾 doesn’t have that problem.

Small, tiny and flipped

• Small caps: ᴏ (U+1D0F)
• Superscript: ᵒ and ᴼ
• Subscript: ₒ, one of the 17 letters that has one
• Upside down: O and o, unchanged, because a circle looks the same rotated
• Mirror: O and o, also unchanged

That symmetry makes O useful in upside-down text: it never looks wrong when flipped.

O in everyday writing

O accounts for about 7.5% of letters in English text, the fourth most common after e, t and a. It also carries meaning on its own: the O in XOXO is a hug, “O” is the vocative in poetry (“O Captain! my Captain!”), and Ø is a separate letter in Danish and Norwegian, not a styled O. The currency style uses Ø for O, so anyone reading Scandinavian text sees a different vowel.

Choosing an O for a monogram

A round O works as a frame. Many monogram layouts put a large O around or behind the other initials. In plain text, the outline 𝕆 or the bold gothic 𝕺 give the most presence on their own. For a handwritten look, see how a cursive O is formed; its closed oval and little top loop are what the script characters imitate.