Where bubble letters come from
White bubble letters (Ⓐ to ⓩ) and circled numbers (① to ⑳) live in the Unicode Enclosed Alphanumerics block, alongside parenthesized letters like ⒜. They have been in Unicode since its early versions, so almost every phone and computer can show them.
Black bubbles (🅐), squares (🄰) and black squares (🅰) come from the newer Enclosed Alphanumeric Supplement, which only includes capital letters. That is why these styles turn everything you type into capitals, and why an older device may show empty boxes instead. Black bubbles use the dingbat numbers ❶ to ❾ with ⓿ for zero, while the square styles leave numbers plain.
The 🅰 🅱 🅾 🅿 surprise
Four black square letters double as emoji: 🅰, 🅱 and 🅾 are the blood type buttons and 🅿 is the parking sign. On some phones and apps they turn into colored emoji buttons while the rest of the word stays black and white. If that mix bothers you, use black bubbles instead, which have no emoji versions.
The parentheses style (⒝⒰⒝⒝⒧⒠) is the quietest option. Its lowercase letters and numbers ⑴ to ⑼ sit in the original block, while its capitals come from the supplement, so a mixed-case word can look a little uneven in some fonts.
Using bubble text well
Bubbles look best on short words: initials, a team tag, a heading in a post or a name in a game lobby. The bubble trail style adds ◦•●◉✿ on both sides for a decorated bio line. Want more round shapes or numbered lists? See circle symbols and number symbols.
Long sentences in bubbles are tiring to read, and screen readers may announce every letter as "circled Latin small letter" followed by the letter. Use bubbles as decoration and keep important details plain. For heavy letters without the circles, try the bold text generator.