Barleycorn
A barleycorn is an old English unit of length, traditionally based on the length of a grain of barley. It is defined as exactly 1/3 of an inch or approximately 8.47 millimeters.
Historically, the barleycorn was used for measuring small lengths and was also the basis for the inch, which was originally considered to be three barleycorns long. It played a role in various traditional measurements, including shoe sizing in English-speaking countries, where shoe sizes were sometimes expressed in barleycorn units.
Although obsolete as a formal unit, the barleycorn remains culturally significant, especially in shoe sizing systems.
Summary:
1 barleycorn = 1/3 inch ≈ 8.47 mm
Based on the length of a grain of barley
Used historically in small measurements and shoe sizing
Mostly of historical and cultural interest today
Light Year
A light year is a unit of distance used in astronomy to measure how far light travels in one year. Light moves extremely fast—about 299,792 kilometers per second—so in one year, it travels roughly 9.46 trillion kilometers (or about 5.88 trillion miles). Light years help scientists express the huge distances between stars and galaxies. For example, the nearest star to Earth, Proxima Centauri, is about 4.24 light years away. The term “light year” can be confusing because it sounds like a measure of time, but it actually measures distance.
No conversions available for length.