barleycorn

Barleycorn is a historical unit of length used in the imperial and US customary measurement systems. It denotes one third of an inch, so three barleycorns comprise one inch. Accordingly, a foot contains 12 inches or 36 barleycorns, and a yard contains 3 feet or 108 barleycorns.

The term derives from the length of a single barley grain and reflects the medieval practice of using natural objects as approximate standards. The name is formed from the Old English words bere (barley) and corn (grain). As a result, “barleycorn” literally means a grain of barley.

In practice, the barleycorn was once used in various measuring contexts and is most famously associated with shoe sizing in Britain, where sizes were commonly expressed in barleycorns or derived from them. Its use declined with the widespread adoption of metric units in the 20th century, but it remains a historical reference in discussions of old measurements and in some niche industries or vintage texts.

In addition to its function as a unit, barleycorn also denotes the seed of the barley plant itself, a cereal grain widely cultivated for food and for brewing. The two senses—the seed and the measurement unit—share the same linguistic root, reflecting barley’s long-standing role in agriculture and daily life.