What ℓ means
The looped form helps distinguish lowercase l from 1. ℓ grew out of practical notation, where plain lowercase l could be mistaken for the digit one. The liter sign l was adopted in 1879; at an international meeting on measurement standards in 1979, both l and L were accepted because of that confusion.
A 1990 proposal about computer character sets traces ℓ’s history to XCCS 2.0, an older character set, and an IBM character identifier. Older library catalogs also used ℓ for “leaf” or “leaves”—one physical sheet of a book. Revised cataloging rules dropped that abbreviation in 1981.
A technical, legacy form; it looks deliberate in ordinary prose.
For SI writing, use ordinary l or L for liter.
What it means when someone sends it to you
3 readingsDon't confuse it with
3Questions people ask
2Is ℓ an SI liter symbol?
No. Unicode 16.0 describes ℓ as a non-SI liter symbol; SI writing uses ordinary l, with L also accepted to avoid confusion.
Is ℓ the same as 𝓁?
No. 𝓁 is a separate character for mathematical script styling; ℓ is the looped letterlike symbol.
How to type ℓ
ℓ\2113Codes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.