Why Shoe Sizes Make No Sense (and How to Actually Find Your Fit)

Three systems. Zero agreement. All based on units nobody uses anymore.

US shoe sizes are based on barleycorns — an old English unit equal to exactly one-third of an inch. A US men's size 1 corresponds to 7⅔ inches (the shoe last, or mold), and each size up adds one barleycorn — ⅓ inch. This system was formalized in the 1800s and has never been updated or metricated.

European sizes are based on Paris points, equal to ⅔ of a centimeter. UK sizes also use barleycorns but start from a different baseline. And none of these systems divide evenly into each other, which is why every conversion chart has ranges instead of clean numbers.

That's the entire explanation for why international shoe sizing is a mess. Three countries developed footwear industries independently, each built on different historical conventions, and nobody's had sufficient economic incentive to standardize globally since.

Why sizes vary within the same system

Even within the US, a size 10 from Nike is not the same as a size 10 from New Balance. Here's why:

• Lasts vary by brand. A "last" is the foot-shaped mold the shoe is built on. Each brand's last has different width, volume, toe box shape, and heel-to-ball proportions. Nike lasts run narrow and low-volume. New Balance builds for wider feet. Same number, different fit.
• No enforcement. No government body verifies that shoes labeled as a given size conform to any foot dimension. The number is brand convention, not specification.
• Width is a whole separate variable that most people don't know exists. The US has a width system (2A through 4E) but most mass-market shoes come in one width only — D (medium men's) or B (medium women's). People with wider or narrower feet perpetually squeeze into the nearest available option or don't understand why shoes never fit right.

Men's size conversion chart

Women's size conversion chart

How to actually find your size

Measure your foot. That's the most reliable method — bypass the nominal sizes entirely and use centimeters directly.

1. Put a piece of paper on a hard floor
2. Stand on it barefoot with your heel against a wall
3. Mark the tip of your longest toe (may be your second toe)
4. Measure from the wall to the mark in centimeters
5. Add 0.5–1 cm (you want some room)
6. Find that measurement in the CM column above

Measure both feet — most people have one slightly larger. Size for the bigger foot. Measure in the afternoon when feet have swelled slightly; a morning measurement gives your smallest size.

Buying shoes online without getting it wrong

• Always check the brand's specific size chart — the conversion charts are guides, not guarantees
• Read reviews for fit notes: "runs narrow," "runs small," "fits true to size" from people with your foot type beats any chart
• For athletic shoes, go a half size larger than everyday shoes — feet swell during exercise, and you need room for socks
• For leather dress shoes, buy true to size — leather stretches, so a slight snugness when new is correct
• Order from retailers with free returns — the try-on-at-home model is the only reliable solution for online shoe shopping