An ell (from Proto-Indo-European *el- "elbow, forearm), when used as a unit of length, is usually 45 inches, i.e. 1.143 m (for the international inch). It is now obsolete and was mainly used in the tailoring business. It was derived from the length of the arm from the shoulder to the wrist, although the exact length was never defined in English law.

Several different national forms existed, with different lengths, including the Scottish ell (approximately 37 inches), and the Flemish ell (approximately 27 inches).

This unit has mostly fallen out of use, as have others based on the human arm:

• digit (1/60 ell),
• finger (7/360 ell),
• palm (1/15 ell)
• hand (4/45 ell),
• shaftment (2/15 ell),
• span (1/5 ell)
• cubit (2/5 ell).

Sometimes ‘ell’ is used as an alias for the cubit.

Units of length | Human-based units of measure

Alen | Elle (Einheit) | Aune | El (lengtemaat) | エル (単位) | Alen | Alen | Łokieć (miara) | Aln | Arşın