What 𝐁 means
As of 2026, type 1D401 in Word for Microsoft 365; press Alt+X.
If other hexadecimal digits immediately precede the value, select only 1D401 before converting. In HTML, 𝐁 is a numeric character reference that produces the same character.
What does mathematical bold B mean?
Its heavier form marks a mathematical distinction; context supplies its value.
Bold type has a long history in print mathematics. In 1886, Oliver Heaviside described using Clarendon, a heavy typeface with small strokes at letter ends, to distinguish vectors—quantities with direction and size—from scalars. Older computer character sets already had a handful of math-styled letters; Unicode extended them into systematic alphabets. In some conventions bold letters denote vectors, but the formula's author determines what B means.
Mathematical bold is semantic on a single symbol; in prose, this remains a separate special character.
For ordinary bold text, use formatting; 𝐁 can interfere with search and accessibility.
What it means when someone sends it to you
2 readingsDon't confuse it with
1Questions people ask
1Can normalization turn 𝐁 into plain B?
Yes. NFKC and NFKD normalization map mathematical alphanumeric letters to their plain Latin or Greek forms, erasing the style distinction.
How to type 𝐁
𝐁\1D401Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.