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Learn Shoe Sizing

History, science, and everything in between. Need the quick charts? → Guide

The History of Shoe Sizing

In 1324, King Edward II of England issued a royal decree that one barleycorn — a third of an inch — would be the standard unit of shoe measurement. Thirty-six barleycorns laid end to end equaled the length of the King's own foot, establishing that length as a size 12. What sounds like a medieval quirk is actually very much alive today: the US and UK still use this exact system, meaning every time you ask for a size 10, you're working with a unit of measurement older than the printing press.

Formal documentation of the system arrived in 1688, when English writer Randle Holme III described shoe sizing in his encyclopedic work 'The Academy of Armoury and Blazon.' By this point the barleycorn scale had already been in use for centuries, and Holme's writing helped cement it as common knowledge among craftsmen and merchants across England.

The early 20th century brought the Ritz Stick, developed somewhere between 1913 and 1916. It was the first nationally recognized foot-measuring device in the United States — a simple flat wooden scale with a heel stop at one end and a sliding toe stop at the other. Crude by modern standards, but a genuine leap forward from asking customers to eyeball their own feet.

The real revolution came from a 22-year-old named Charles Brannock. Between 1925 and 1927, working in his father's shoe store in Syracuse, New York, Brannock built his first prototype from pieces of an Erector set toy — a child's construction kit. He received his patents in 1926 and 1927 for a device that measured three dimensions simultaneously: total foot length, arch (heel-to-ball) length, and ball-of-foot width. The result was a fitting accuracy of 95 to 96 percent, a dramatic improvement over anything that had come before. By 1939, over 33,000 Brannock Devices were in use worldwide. The design has barely changed since — the one in your local shoe store today is essentially Brannock's original invention.

International Sizing Systems

The US system is built on the barleycorn, with each full size representing one-third of an inch of foot length and each half size representing one-sixth of an inch. The math behind it: for men's sizes, take the foot length in inches, multiply by three, and subtract 22. For women's, subtract 21 instead. These separate scales mean men's and women's sizes are not directly comparable — a women's size 9 is physically a different shoe than a men's size 9, built on a different last.

The UK system shares the same barleycorn foundation but uses a different starting offset: the formula is foot length in inches times three, minus 23, applied the same way for both men and women. That unisex approach means the gender arithmetic is simpler, but the offset from US sizing varies by sex: US men's sizes run about one size larger than UK, while US women's sizes run about two sizes larger than UK. So a UK 7 is a US men's 8 but a US women's 9.

Continental Europe uses the Paris Point, invented by French shoemakers in the early 19th century. One Paris Point equals two-thirds of a centimeter, or about 6.67 millimeters. The scale is unisex, which makes cross-gender comparisons straightforward, but there's an important catch: EU sizes measure the shoe's last (the foot-shaped mold inside the shoe), not the foot itself. The last is typically about 1.5 centimeters longer than the foot to allow for toe room, which is why EU sizes can seem puzzlingly large when you first encounter the conversion charts. Half sizes are also rare in EU sizing, which is one of its genuine weaknesses.

Mondopoint — codified as ISO 9407 and used in Russia, China, Japan, Korea, and parts of Eastern Europe — throws out the historical baggage entirely. Your shoe size is simply your foot length in millimeters, sometimes combined with width in a format like 260/95 (260mm long, 95mm wide at the ball of the foot). Japan uses centimeters rather than millimeters, so a Japanese size 26 equals a Mondopoint 260. It's the most logical system by far, and it's the only one where the size number directly tells you something real about your foot. The fact that it hasn't conquered the world says a lot about how deeply entrenched historical systems can be.

Men's vs. Women's Sizing

The standard offset between US men's and women's shoe sizes is 1.5 sizes — a women's size 9 corresponds to a men's size 7.5, and a men's size 10 corresponds to a women's size 11.5. This offset exists because men's and women's shoes are built on different lasts, not just relabeled versions of the same shoe. The lasts differ in proportions across the heel, instep, and forefoot, meaning the conversion is an approximation rather than a perfect match.

That 1.5-size offset is a guideline, not an industry standard, and brands interpret it differently. Adidas uses a 1.0-size offset in many of their styles. New Balance and Converse both use 2.0. Nike tends to hover around 1.5 but varies by silhouette. When someone recommends 'just buy a men's shoe if you can't find your women's size,' they're glossing over the fact that you may also need to account for width — a men's D width is wider than a women's D width, because men's lasts are proportionally broader even at the same labeled width letter.

The UK and EU systems sidestep the gender offset problem entirely. UK sizing uses a single unisex scale, and EU sizing via the Paris Point is also unisex. This makes cross-gender comparisons in those systems genuinely straightforward: a UK 7 is a UK 7, regardless of who's wearing it. If you find yourself doing a lot of international size conversions, keeping a unisex reference point — like your EU size — can simplify the math considerably.

Factors Beyond the Number

A shoe size is a starting point, not a guarantee of fit. The number captures foot length and, if you're lucky, some indication of width — but a remarkable number of variables can make a technically correct size feel completely wrong. Understanding them turns shoe shopping from guesswork into something closer to a science.

Arch Height

High arches concentrate pressure on the heel and ball while leaving a gap in the midfoot. Low or flat arches spread the foot more broadly. High-arched feet often need more midfoot volume or removable insoles to add structure; flat feet typically need firm arch support built into the shoe itself.

Instep Height

The instep is the top of your foot between the ankle and toes. A high instep means low-cut openings, tight straps, and rigid tongue designs will feel constricting even when the length is perfect. Lace-up shoes give more room to adjust; slip-ons and low-cut sneakers can be genuinely unwearable for high-instep feet.

Heel-to-Ball (Arch) Length

The Brannock Device measures this separately from total foot length. Your arch length is the distance from your heel to the ball of your foot — where your foot bends when you walk. If your arch length and total length suggest different sizes, fit to the arch length. A shoe that's too long in total but correct in arch length will at least bend in the right place.

Toe Box Shape

Pointed toe boxes compress the toes laterally, regardless of what the size label says — they're largely decorative and can cause bunions and neuromas over time. Round toe boxes leave more room for natural toe position. Square or wide toe boxes most closely mimic the actual shape of human feet and allow the toes to splay naturally during the push-off phase of walking.

Materials

Leather stretches — sometimes up to a full size over the course of months of wear as the fibers soften and conform to your foot. Synthetic materials like PU and most athletic mesh barely stretch at all. Knit and engineered mesh uppers are forgiving and accommodating from day one. Patent leather is rigid and does not stretch, which is why patent formal shoes must fit perfectly in the store or they never will.

Foot Volume

Two feet can have identical length and width measurements but very different total volume — the overall amount of space the foot takes up. Volume affects fit most dramatically in boots and closed-toe shoes, where the upper needs to conform to the entire foot rather than just grip at specific points. High-volume feet often feel cramped in athletic shoes; low-volume feet may find boots sloppy and prone to heel slippage.

Sock Thickness

This one is obvious once you think about it, but many people size shoes while wearing thin dress socks and then wear them with thick wool hiking socks. A half-size of difference in effective foot length is easy to generate just by changing sock thickness. Always try on shoes — especially athletic shoes and boots — while wearing the socks you'll actually use them with.

Time of Day

Feet swell due to gravity and activity throughout the day, typically by at least half a size between morning and late afternoon. Shoes that fit perfectly at 10am may feel tight by 4pm. For this reason, shoe fitting professionals recommend measuring and trying on shoes in the late afternoon or evening, when your feet are at their largest.

Foot Asymmetry

The vast majority of people have one foot larger than the other — sometimes by a half size, occasionally by a full size. The difference is usually small enough to accommodate in a single pair of shoes, but when it isn't, always buy for the larger foot and address the fit on the smaller side with an insole or thicker sock. Buying for the smaller foot guarantees problems.

Activity Type

Running shoes are typically sized 0.5 to 1 full size larger than casual shoes to account for forward foot movement inside the shoe and the swelling that comes with sustained aerobic exercise. Hiking boots need extra toe room specifically for downhill descents, where the foot slides forward. Dress shoes fit snugger and trim. Rock climbing shoes are deliberately sized one to two sizes down for a tight, precise fit that allows force transmission through the toe.

Glossary

Key terms you'll encounter when shopping for shoes or reading size charts.

Arch Length: The heel-to-ball measurement — the distance from the heel to the ball of the foot. The Brannock Device measures this separately from total length. When arch length and total length suggest different sizes, fitting to arch length generally produces better results.
Ball of Foot: The widest part of the foot, located at the base of the toes. Shoe width is measured at this point, and the Brannock Device uses it as the reference for width measurement.
Barleycorn: The traditional unit of shoe measurement, equal to one-third of an inch. Dating to a 1324 royal decree by King Edward II, it remains the basis of US and UK shoe sizing.
Brannock Device: The standard metal foot-measuring instrument invented by Charles Brannock in the 1920s. Measures total foot length, heel-to-ball (arch) length, and ball-of-foot width simultaneously.
Instep: The top surface of the foot between the ankle and the toes. Instep height varies significantly between individuals and affects how well closed-toe shoes, straps, and low-cut openings fit.
Last: The foot-shaped mold around which a shoe is constructed. Lasts determine the shoe's internal shape, volume, and proportions. EU sizes are measured from the last, not the foot.
Mondopoint: An ISO international shoe sizing standard (ISO 9407) in which the size number equals the foot length in millimeters, sometimes paired with width. Used in Russia, China, Japan, and Korea.
Paris Point: The unit of measurement for EU shoe sizes, equal to two-thirds of a centimeter (6.67mm). Invented by French shoemakers in the early 19th century. Each EU size increment is one Paris Point.
Relaxin: A hormone produced during pregnancy that loosens ligaments throughout the body. It can permanently flatten and widen the feet, causing many women to move up one or more shoe sizes after pregnancy.
Ritz Stick: Developed between 1913 and 1916, the Ritz Stick was the first nationally recognized foot-measuring device in the United States — a flat wooden scale with a heel stop and sliding toe stop.
Toe Box: The front section of a shoe that surrounds and covers the toes. Toe box shape — pointed, round, or square — determines how much lateral space the toes have regardless of the shoe's length.
Width Designation: A letter code indicating the proportional width of a shoe relative to its length. Standard widths are D for men and B for women. The full scale runs from AAA (narrowest) to 6E (widest). Each increment adds approximately 3/16 inch at the ball of the foot.

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