Blackboard Bold, Straight From Mathematical Unicode
Type your text and get the hollow, double-outlined letterforms mathematicians call "blackboard bold" — originally a chalkboard trick of drawing a bold letter twice with a slight offset, now a real Unicode style you can copy and paste anywhere.
This isn't a custom font — every letter and digit is swapped for its counterpart in Unicode's Mathematical Alphanumeric Symbols block, which is why the double-struck look survives being pasted into any plain-text field, with no font installation required.
Why do some letters look different from the rest?
Seven uppercase letters — C, H, N, P, Q, R, and Z — use a different, older set of Unicode code points than the other nineteen. That's because ℂ, ℍ, ℕ, ℙ, ℚ, ℝ, and ℤ were already part of Unicode's Letterlike Symbols block long before the Mathematical Alphanumeric Symbols block existed, since mathematicians have long used double-struck capitals for specific number sets: ℝ for real numbers, ℂ for complex numbers, ℤ for integers, ℕ for natural numbers, and ℚ for rationals. Rather than duplicate those seven letters, Unicode reuses the originals — so this tool does too, matching the real math notation exactly.
Does this convert numbers too?
Yes. Digits 0–9 have their own dedicated double-struck Unicode range and convert automatically alongside the letters, with no gaps or reused code points.
Where can I use double-struck text?
Anywhere that supports Unicode characters, including Instagram, Twitter/X, Facebook, TikTok, and Discord bios, captions, comments, messages, and usernames, as well as documents and emails. You can pair it with other Unicode styles like bold text or italic text to create varied formatting within the same post.
Related tools
- Bold Text Generator — six bold Unicode styles for a different kind of emphasis.
- Bubble Text Generator — circled Unicode letters in outlined and filled styles.
- Mirror Text Generator — flips your text into horizontally mirrored writing.
Last reviewed: August 2026