Shoe size systems explained: US, UK, EU, Mondopoint
UK and US sizes count thirds of an inch, EU sizes count thirds of two centimetres, and Mondopoint simply states the foot length in millimetres. Knowing this explains most of the confusion around shoe sizes.
Last updated: September 28, 2026
How each system is derived from a length
| System | Step is called | Defined as | Full size (mm) | Half size (mm) |
|---|---|---|---|---|
| UK and US | Barleycorn | 1/3 in | 8.47 | 4.23 |
| EU | Paris point | 2/3 cm | 6.67 | 3.33 |
| Mondopoint, Japan | Millimetre steps | 5 mm | 5.00 | — |
An EU size step is shorter than a UK or US step: four EU sizes are 26.67 mm, three UK sizes are 25.4 mm. The systems never line up exactly, so every conversion chart has to round.
UK sizes
UK sizes count barleycorns, an old unit of one third of an inch. The scale has two parts: children’s sizes run from 0 to 13, with half sizes, then the numbering starts again at 1 for adults. The same scale is used for women and men.
From foot length: divide by 8.47 mm, add 2 for the room in the shoe, and subtract 25 for an adult size or 12 for a child size.
US sizes
US sizes use the same step as UK sizes but start at a different point, and they differ between men and women. In practice a US men’s size is the UK size plus 1, and a US women’s size is usually the UK size plus 2.
The Brannock device is a foot-measuring instrument from the United States. Its maker defines men’s size 1 as 7 2/3 inches, with one third of an inch for each further size and one sixth for a half size. That is the same as the UK formula plus 1.
Widths are lettered. The Brannock device distinguishes nine widths from AAA to EEE, 3/16 inch apart. The width that belongs to a letter grows with the length of the shoe.
EU sizes
EU sizes, formerly called Paris points, French or Continental sizes, count steps of two thirds of a centimetre from zero. There is one scale for children and adults, women and men.
From foot length: divide by 6.67 mm and add 2. A foot of 24 cm gives 240 divided by 6.67, plus 2, which is 38.
The conversion specification notes that the EU system is read as a foot length system in some countries and as a last length system in others. This is one reason why EU labels vary more between manufacturers than the other systems.
Mondopoint, Japan, China and Korea
Mondopoint is the system of the international standard ISO 9407. A size is the length of the foot the shoe is intended to fit, in millimetres, usually in steps of 5 mm.
Japan, China and the Republic of Korea designate the length of a shoe by foot length as well. Japanese sizes are written in centimetres or millimetres: 26.5 and 265 mean the same foot. The current Chinese standard adopts ISO 9407 with modifications.
By definition these systems need no conversion chart: measure your foot and you have your size. Brand labels can still deviate; two sports brands we checked print 28 cm for a foot of 27.1 cm.
Why brand charts disagree
The standards are voluntary, and every brand publishes its own chart. The table shows what four brand charts print for nearly the same foot.
| Chart | Foot length | US men's | UK | EU |
|---|---|---|---|---|
| This page (formulas) | 27.1 cm | 10 | 9 | 42.5 |
| Nike | 27.1 cm | 10 | 9 | 44 |
| adidas | 27.1 cm | 10 | 9.5 | 44 |
| New Balance | 27 cm | 9 | 8.5 | 42.5 |
| Clarks | 10.7 in (27.2 cm) | 10 | 9 | not listed |
The charts agree within about one size, but not exactly. If the brand publishes a chart with foot lengths, use your foot length and that chart. Use this page when the seller gives no chart, or to understand what a size label roughly means.
How to use the formulas when you buy
- Measure your longer foot in millimetres.
- Calculate the size in the system of the shop, or look it up in one of the charts.
- Open the size chart of the brand and find the row with your foot length. If its size differs from the calculated one, the brand chart decides.
Worked example: one foot in four systems
A foot measures 25.0 cm.
- Mondopoint: 250. Japan: 25.0.
- EU: 250 divided by 6.67 is 37.48. Plus 2 is 39.48, rounded to 39.5.
- UK: 250 divided by 8.47 is 29.52. Plus 2, minus 25, is 6.52, rounded to 6.5.
- US: men’s 6.5 plus 1 is 7.5; women’s 6.5 plus 2 is 8.5.
Common mistakes
- Treating a conversion as exact. Every conversion rounds, and brands round differently.
- Reading a Japanese 26 as an EU or US size. It is a foot length in centimetres.
- Subtracting a fixed number to get from EU to UK sizes. The steps differ, so the difference changes along the scale.
- Expecting children’s and adult sizes to continue. UK and US numbers restart after 13.5.
Sources and checks
The values in the chart are calculated from the definitions in the sources below. They are not copied from another chart. Last checked against the sources on September 28, 2026.
Step lengths are calculated from the definitions: a barleycorn is one third of an inch of 25.4 mm, a Paris point is two thirds of a centimetre.
Half sizes exist in the UK, US and EU systems. Mondopoint has no half sizes; its usual step is 5 mm.
Used for: The formulas that give UK and EU sizes from foot length, the size steps of 8.47 mm and 6.67 mm, the allowance of two sizes between foot and last, and the usual offsets of US sizes from UK sizes.
Used for: The current edition of the conversion standard and its statement that its adult tables are a guideline. Its tables were not read.
Used for: The barleycorn of one third of an inch, half sizes of one sixth of an inch, children's sizes that run to 13 before adult sizes restart at 1, and UK women's 5 being US women's 7.
Used for: US men's size 1 corresponds to 7 2/3 inches, each further size adds 1/3 inch, and widths are 3/16 inch apart.
Used for: Mondopoint designates a shoe by the foot it is intended to fit.
Used for: The usual Mondopoint step of 5 mm and the marking in millimetres.
Used for: Japanese shoe sizes are based on foot length.
Used for: The Chinese shoe size standard in force since May 2023 adopts ISO 9407:2019 with modifications.
Used for: Example of a brand chart: the sizes printed for a foot length of 27.1 cm.
Used for: Example of a brand chart: the sizes printed for a heel to toe length of 27.1 cm.
Used for: Example of a brand chart: the sizes printed for a length of 27 cm.
Used for: Example of a brand chart: the sizes printed for a foot length of 10.7 inches.
Frequently asked questions
- What is a barleycorn?
- An old English unit of one third of an inch, about 8.47 mm. It is the step between two full UK or US shoe sizes. A half size is one sixth of an inch.
- What is a Paris point?
- Two thirds of a centimetre, about 6.67 mm. It is the step between two full EU shoe sizes.
- Is there an international standard for shoe sizes?
- Yes. ISO 9407 defines Mondopoint, which marks shoes by foot length in millimetres, and ISO 19407 describes how to convert between systems. Both are voluntary, and the conversion standard calls its adult tables a guideline.
- Which system is the most reliable when buying abroad?
- Foot length. If the seller states the foot length in centimetres or millimetres for each size, compare it with your own measurement and ignore the other labels.
- Why is my EU size different in every brand?
- EU sizes are read as foot length based in some places and last length based in others, and brands build on their own lasts. In the charts we compared, the same foot is EU 42.5 in one brand and EU 44 in two others.