Is this CSS bold or real characters?

These are real Unicode characters from the Mathematical Bold block, not formatting. Because they are distinct code points, the bold look is preserved when copied into apps that only accept plain text.

Which characters can it convert?

Uppercase A–Z map from U+1D400, lowercase a–z from U+1D41A, and digits 0–9 from U+1D7CE. Spaces and punctuation are left unchanged because the block does not define bold forms for them.

Where is this useful?

Anywhere you cannot apply real formatting — Instagram and Twitter bios, LinkedIn headlines, Discord names, and YouTube titles — but want certain words to stand out in bold.

Will it look right on every device?

Most modern fonts include the Mathematical Bold glyphs, so it renders on the web, mobile, and chat apps. A few older fonts lack them and show boxes instead.

Should I use it for body text?

No. Screen readers may announce these as math symbols, and search engines treat them differently from normal letters, so reserve them for short accents rather than full sentences.

Bold Serif Unicode Text

Make words bold anywhere

Many platforms — social bios, usernames, chat handles — strip out real formatting, so you cannot simply bold a word. Unicode solves this with a Mathematical Bold alphabet: a complete set of bold serif letters and digits that are genuine characters. This tool maps your text onto that block so the bold styling travels with the text wherever you paste it.

How it works

The Mathematical Bold block lays out letters and digits in order, so each character is found by adding an offset to a base code point:

bold capital = 0x1D400 + (letter - "A")
bold small    = 0x1D41A + (letter - "a")
bold digit     = 0x1D7CE + (digit  - "0")

Anything outside A–Z, a–z, and 0–9 — spaces, punctuation, symbols — is passed through untouched because the block does not define bold variants for those. The output is therefore a mix of bold glyphs for letters and digits and your original characters for everything else.

Tips and notes

Use bold Unicode for short emphasis — a name, a headline word, a price — rather than whole paragraphs, because screen readers may read the glyphs as math symbols and search engines index them differently from plain letters. If a character shows up as an empty box on an older device, that device’s font lacks the glyph. For a more ornate decorative style, try the Old English Fraktur transformer instead.