Why Shoe Sizes Are a Mess
There is no single international standard in common use. Each system evolved separately, measures something slightly different, and none of them measures your foot directly.
| System | Measures | Step size |
|---|---|---|
| US and UK | Last length in barleycorns (1/3 inch) | 1/3 inch per full size |
| EU (Paris point) | Last length in 2/3 cm units | 6.67 mm per size |
| Japan / Mondopoint | Actual foot length in cm | 5 mm |
The barleycorn is genuinely medieval: English shoe sizes have been based on the length of a grain of barley since the fourteenth century, and three barleycorns make an inch. Mondopoint, used by the military and for ski boots, is the only system that states foot length directly — and it is the one nobody sells shoes in.
Conversion Rules of Thumb
- US men to UK: subtract 1
- US women to UK: subtract 2
- US men to US women: add 1.5
- US men to EU: add roughly 33
- EU to foot length: (EU − 1.5) ÷ 1.5 = length in cm
Men's Size Chart
| Foot length | US | UK | EU | Japan |
|---|---|---|---|---|
| 24.3 cm | 6 | 5 | 38 | 24.5 |
| 25.1 cm | 7 | 6 | 39 | 25 |
| 25.9 cm | 8 | 7 | 40 | 26 |
| 26.8 cm | 9 | 8 | 42 | 27 |
| 27.6 cm | 10 | 9 | 43 | 27.5 |
| 28.5 cm | 11 | 10 | 44 | 28.5 |
| 29.3 cm | 12 | 11 | 45 | 29.5 |
| 30.2 cm | 13 | 12 | 47 | 30 |
Women's Size Chart
| Foot length | US | UK | EU | Japan |
|---|---|---|---|---|
| 22.1 cm | 5 | 3 | 35 | 22 |
| 23.0 cm | 6 | 4 | 36 | 23 |
| 23.8 cm | 7 | 5 | 37 | 24 |
| 24.7 cm | 8 | 6 | 39 | 24.5 |
| 25.5 cm | 9 | 7 | 40 | 25.5 |
| 26.4 cm | 10 | 8 | 41 | 26.5 |
| 27.2 cm | 11 | 9 | 42 | 27 |
How to Measure Your Foot
- Stand on a sheet of paper against a wall, heel touching it, wearing the socks you intend to use.
- Put your weight on the foot — feet lengthen under load by several millimetres.
- Mark the tip of the longest toe, which is not always the big toe.
- Measure from the wall to the mark.
- Repeat for the other foot and use the larger figure.
- Measure in the late afternoon or evening, when feet are at their largest.
Feet swell by up to 5% over a day and after exercise. A shoe fitted first thing in the morning will often feel tight by evening.
Width
| US code | Meaning |
|---|---|
| AA / 2A | Extra narrow |
| B | Narrow (men) / standard (women) |
| D | Standard (men) / wide (women) |
| E / 2E | Wide |
| 4E / 6E | Extra wide |
The UK uses letters F, G and H; the EU has no widely used width system at all, which is why European sizing often fits poorly for very narrow or very wide feet.
Why Brands Differ
The size is a property of the last — the mould the shoe is built around — not of your foot. Every brand designs its own lasts, and manufacturing tolerance adds several millimetres more. A half-size difference between brands is entirely normal, and a full size is not unusual.
Running shoes are typically bought a half size larger than dress shoes, because feet swell during running and toes need clearance on the downhill. The general rule is about 1 cm of space beyond the longest toe.
Children's Sizes
Children's feet grow roughly half a size every two to four months up to age four, and every four to six months afterwards. Check the fit every couple of months rather than relying on a size, and allow 1–1.5 cm of growing room — but no more, since an oversized shoe changes gait and causes tripping.
Frequently Asked Questions
Is a US men's 9 the same as a women's 9?
No. Women's sizes run about 1.5 larger for the same foot, so a men's 9 is roughly a women's 10.5.
Should I size up for running shoes?
Usually by half a size. Feet swell during a run and need room at the toes, particularly on descents.
Why does the same size fit differently in two brands?
Because each brand uses its own last shape and tolerances. Foot length is the only stable measurement; the size number is a brand's interpretation of it.
What is Mondopoint?
A system that states the actual foot length in millimetres, used for ski boots and by several armed forces. It is the most logical system in existence and almost nobody sells everyday shoes in it.