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From Fields to Feet: The Ancient Barleycorn Secret Behind Your Shoe Size
Did you know modern shoe sizes are based on an ancient unit of measurement called the barleycorn? Defined as 1/3 of an inch by English royalty in 1324, this medieval standard dictates the seemingly arbitrary numbers on your shoes using a simple, centuries-old formula. It's a true historical relic.
A Measurement Fit for a King
Have you ever stood in a shoe store, baffled by the numbers? A size 10 in one brand fits perfectly, while in another, you're squeezing into an 11. It seems arbitrary, but the origin of this system is anything but random. It’s rooted in agriculture and a royal decree from nearly 700 years ago. The standard unit for shoe measurement is the barleycorn.
Yes, that's right—a grain. In 1324, King Edward II of England, in a statute titled Statutum de Pede et Pollicis, formally defined the inch as equal to "three grains of barley, dry and round, placed end to end." This established the barleycorn as 1/3 of an inch, and it became the foundational unit for countless measurements, including shoemaking. The system was simple and based on what was commonly available, creating a surprisingly enduring standard.
The Curious Math of Modern Sizing
So how do we get from a grain to the number on your sneaker? The formula, at least for the UK and US systems, is a direct descendant of this medieval standard. A shoemaker's ruler, known as a size stick, begins at a baseline size and increases by one barleycorn (1/3 inch) for each whole size up.
The specific formula used in North America is:
Men's Shoe Size = (3 × foot length in inches) − 23
For women, the constant is slightly different:
Women's Shoe Size = (3 × foot length in inches) − 22
As one person on the internet worked out, this means a size 10 men's foot is about 11 inches long. The math checks out: (3 * 11) - 23 = 10. This simple calculation has been the bedrock of sizing for centuries.
So you're telling me my size 10 foot is 11 inches long? So 3 * 11 = 33 - 23 = size 10. Neat.
From Standard to... Suggestion?
While the barleycorn system provides a historical standard, anyone who has shopped for shoes knows it's more of a guideline today. Variations in manufacturing, different lasts (the mechanical form a shoe is shaped on), and a lack of enforcement mean that a size can vary dramatically from one company to the next.
This is why the Brannock Device, that metal contraption you find in shoe stores, measures not just length but also width and arch length—providing a more accurate, standardized starting point. Yet, even with these tools, the ancient barleycorn remains the ghost in the machine, a fascinating and quirky piece of history that dictates why you wear the number you do. The next time you try on a pair of shoes, remember you're not just dealing with modern manufacturing, but with a decree made by an English king and the humble grain he chose as his standard.