Barleycorn (bc)

Medieval EnglishHistorical unit (no longer in standard use)

One third of an inch. A medieval English unit defined as the length of a grain of barley; the origin of the shoe-size increment.

1 barleycorn = 0.008466666667 meters (approximately).

About the barleycorn

Three dry, round grains of barley laid end to end made an inch, according to an English statute known as the Composition of Yards and Perches, dated about 1300. The idea is older still, since the Welsh Laws of Hywel Dda in the 10th century used a similar rule. A barleycorn is therefore one third of an inch, about 8.47 mm, although Wikipedia's infobox rounds it to 8.46 mm. Wiktionary describes the word simply as a compound of barley and corn, meaning grain.

Real barley kernels range from roughly 4 to 15 mm depending on the cultivar, and older sources put the average near 8.8 mm, so the grain gave a notion of size, not a precise standard. Formal standards were later set by comparison with a reference yard bar, with the barleycorn taken as 1/108 of its length. A line is a quarter of a barleycorn and a poppyseed a quarter or fifth. The unit lives on mainly in shoe sizing in some English-speaking countries, where each size step is one barleycorn.

Sources: Wikipedia: Barleycorn (unit); Wiktionary: barleycorn

Barleycorn conversion chart

1 barleycorn expressed in every other length unit:

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