Handspan

Handspan, also called span, is a traditional unit of length defined as the distance from the tip of the thumb to the tip of the little finger when the hand is fully extended and spread. Because the measurement depends on hand size and the amount of finger spread, it varies between individuals and populations and has no fixed universal value.

In adults, a typical handspan covers roughly 18 to 25 centimeters (about 7 to 10 inches), with many estimates centering around 20 to 23 cm for an average adult. Women generally have slightly smaller spans on average than men, reflecting differences in hand size, but there is wide variation within any group.

Historically, handspan served as an informal, human-scale unit of measurement in many cultures before the adoption of standardized metric or imperial units. Today it is rarely used in scientific or engineering contexts, but the term persists in anthropometric references, in crafts, and in activities that involve measuring by feel, such as archery, climbing, or tailoring.

Because it is not standardized, handspan should be treated as a rough measure rather than a precise quantity. When precision is required, standard units such as centimeters or inches should be used, and if handspan is used, it should be accompanied by the measured value for transparency.

See also: Span (unit of length), Handbreadth, Anthropometry.