Bold Text Generator (Unicode bold letters for social media bios & posts)

Understanding the bold text generator — concept and principle

Social media bios, captions and many messaging apps accept only plain text, so you cannot simply press a bold button. This generator works around that by swapping each Latin letter and digit for a look-alike character from Unicode, giving bold, bold sans-serif, bold italic, bold script and bold Fraktur versions you can copy and paste anywhere that shows Unicode.

How it is calculated

For each character c:

• A–Z → style start (capital) + (c − 'A')
• a–z → style start (small) + (c − 'a')
• 0–9 → style start (digit) + (c − '0'), only for bold and bold sans-serif

Bold capital A is U+1D400, bold small a is U+1D41A and bold digit 0 is U+1D7CE; each following letter is the next code point.

A few letters that were encoded earlier in the Letterlike Symbols block (such as script capital B, U+212C) replace gaps in the mathematical block.

Other characters stay as typed. Length in UTF-16 units counts 2 per restyled character.

The principle

Unicode includes a block called Mathematical Alphanumeric Symbols, designed so that mathematicians can use bold, italic, script and other letter styles as distinct symbols. Because they are separate characters rather than formatting, they survive copying into places that strip formatting. The letters are arranged in alphabetical order, so converting is just an offset. These characters lie outside the Basic Multilingual Plane, which is why each one needs two UTF-16 code units, and why some apps count your text as longer.

Worked example

Default input: "Hello World 2026".

1. H (U+0048) becomes U+1D400 + 7 = U+1D407, bold 𝐇; e becomes U+1D41A + 4 = 𝐞, and so on.
2. Bold (serif): 𝐇𝐞𝐥𝐥𝐨 𝐖𝐨𝐫𝐥𝐝 𝟐𝟎𝟐𝟔; bold sans-serif: 𝗛𝗲𝗹𝗹𝗼 𝗪𝗼𝗿𝗹𝗱 𝟮𝟬𝟮𝟲.
3. Italic, script and Fraktur styles have no digits, so "2026" stays plain in those.
4. Letters restyled = 10; characters left as typed = 2 (the spaces).
5. UTF-16 length of the bold version = 10 × 2 + 4 × 2 + 2 = 30.

How to read the result

Pick a style that suits your post and copy it. Use it sparingly: screen readers may read each mathematical letter by name or skip it, which makes the text hard for blind and visually impaired users to understand. Search engines and in-app search may also not match these characters to normal words. Some fonts lack these characters and show empty boxes.

Common mistakes

• Using styled letters for whole paragraphs, which hurts accessibility.
• Expecting accented letters, Hangul or emoji to change; they have no bold twins.

Frequently asked questions

Why does my bold text look like boxes on some devices?

The device's fonts do not include those Unicode characters.

Can screen readers read Unicode bold text?

Often poorly; they may read each letter as a maths symbol or skip it.

Why does my bio exceed the character limit?

Each styled character can count as two units in apps that count UTF-16.

Sources: The Unicode Standard 15.1, Mathematical Alphanumeric Symbols block (U+1D400–U+1D7FF) and Letterlike Symbols block (U+2100–U+214F) · Unicode Technical Report #25, "Unicode Support for Mathematics"