Why Does Fancy Text Show Boxes?

What is the difference between boxes, question marks and �?

The 3 symptoms look similar but have 3 different causes, and only the first is fixable on the reader's side:

The � case is specific to fancy text. Each Mathematical Alphanumeric letter, such as 𝐀, takes 2 UTF-16 code units. An app that truncates text at a UTF-16 unit limit can split one of these pairs, and the half-character left over turns into �.

Why does fancy text show boxes on some phones and not others?

Boxes appear only on devices whose fonts do not cover the specific characters, so the same text renders differently per device. Font coverage depends on the operating system version and the app. 3 facts determine the outcome:

1. Windows ships Cambria Math with Windows Vista and later, and Chromium-based browsers on Windows fall back to Cambria Math, then Segoe UI Symbol, for the Mathematical Alphanumeric Symbols block. On a Windows 11 test machine, Cambria Math contained glyphs for 996 of the block's 997 characters.
2. Google's Noto fonts exist to remove tofu: Google's developer blog states that "Noto" stands for "No more tofu". Android and ChromeOS use Noto as their fallback font family.
3. Characters added recently show as boxes on nearly every device, because fonts update years after Unicode releases. The table below lists the 4 recent additions that fancy text sites sometimes use.

The generators on this site leave those letters plain instead of using the new characters. The small text generator therefore prints a normal q and x in small caps, and a normal q in tiny text.

Which fancy text styles are least likely to show boxes?

Styles built from older, widely covered blocks are least likely to show boxes. Ranked from safest to riskiest, the 6 main groups are:

1. Combining marks on plain letters (strikethrough a̶b̶c̶, underline a̲b̲c̲): the base letters are ASCII, and the marks have been in Unicode since version 1.1 (1993).
2. Fullwidth letters (ａｂｃ) and circled letters (ⓐⓑⓒ): both in Unicode since version 1.1 (1993) and covered by the standard Chinese, Japanese and Korean system fonts.
3. Mathematical alphabets: bold, italic, sans-serif, script, Fraktur, double-struck and monospace, all from Unicode 3.1 (2001).
4. Small caps (ᴀʙᴄ): drawn from 3 blocks of different ages, so one letter can come from a different fallback font than its neighbors.
5. Black circled and squared letters (🅐🅑🅒 🅰🅱🅲): from the Enclosed Alphanumeric Supplement. 🅰 🅱 🅾 🅿 are also emoji, so many systems draw those 4 in color while the rest stay monochrome. The square text generator page shows the effect.
6. Rare symbols and recent additions, such as the 4 characters in the table above, decorative Egyptian hieroglyphs (𓂃) and Wingdings look-alikes.

How do you fix fancy text that shows boxes?

The fix depends on whether you see the boxes or your readers do. There are 5 steps, in order:

1. Check the text on a second device. If it displays correctly there, the text is intact and the first device lacks a font.
2. Update the operating system and the app. System updates add fonts and fallback rules.
3. Install fonts on a desktop computer. Noto Sans Math covers the Mathematical Alphanumeric Symbols block, and Noto Sans Symbols 2 covers many decorative symbols.
4. Switch to a safer style from the list above, such as bold or strikethrough, if your audience uses older devices.
5. Re-copy the text if you see � or plain question marks. Those characters are permanently lost in the damaged copy.

Can other people see boxes in my bio when I see fancy text?

Yes. Each viewer's device draws the text with its own fonts, so a bio that looks correct on your phone can show boxes on a follower's older phone or computer. Test important text, such as a profile name, on at least one Android device, one iPhone and one Windows computer before relying on it.