Shoe Size Converter

How the shoe size converter works

Every shoe size system counts length. US and UK sizes count in thirds of an inch, EU sizes in steps of two thirds of a centimeter, and Mondopoint simply writes down the foot length in millimeters. Because they all measure the same thing, the honest way to convert between them is through a length: your foot. That is what this converter does. It turns your foot length, or a size you already wear, into a position on each scale and shows the nearest size together with the exact reading, so you can see when you sit between two sizes.

The systems differ in their unit, in where they start counting and in whether they count the foot or the last, the foot shaped form a shoe is built on. Those starting points are conventions, and the charts that publish them do not always agree. Where they disagree, the converter shows you both readings instead of hiding the gap.

The length units behind each system

• The barleycorn, 1/3 inch. English sizes grew out of the old rule that three grains of barley make an inch. In its history of sizing systems, the footwear research body SATRA cites a description from 1856 of one third of an inch between sizes. Both UK and US sizes still step by 1/3 inch, and a half size is 1/6 inch.
• US men's and women's. On the Brannock Device, a foot measuring tool made in the US, a men's size 1 is 7 2/3 inches and each further size is 1/3 inch longer. On Brannock's size comparison chart the women's scale sits exactly one size above the men's.
• UK. The same Brannock chart puts UK adult sizes half a size below US men's. SATRA's examples put them a full size below.
• The Paris point, 2/3 cm. Continental European sizes grew from the metric system, and one full size is 2/3 cm, about 6.7 mm. On the Brannock chart EU 42 lines up with UK 8, which matches SATRA's example of a UK women's 8 as an EU 42.
• Mondopoint, millimeters. The international standard ISO 9407, current edition 2019, sizes footwear by measurements of the foot it is meant to fit. BSI's summary points out that sizes written in centimeters, such as 26.5 for 265, or sizes based on the last rather than the foot do not conform to it. SATRA gives the steps as 5 mm.

The first three formulas follow from Brannock's figures: 7 2/3 inches times 3 is 23, minus 22 gives size 1. The EU formula places EU 42 at the foot length of Brannock UK 8, 10 1/6 inches or 25.8 cm, and adds one size for every 2/3 cm. An inch is exactly 2.54 cm by definition (NIST).

Where the systems do not line up

Because the steps differ, the sizes never line up exactly. One US or UK size is 1/3 inch, about 8.5 mm, while one EU size is about 6.7 mm, so an EU size is a little more than half a US size. A US men's 9 reads 42.6 on the EU scale, which is why one brand labels it 42 1/2 and another 43. The converter rounds US and UK sizes to the nearest half size and EU sizes to the nearest whole size, and always shows the reading underneath.

The UK is the clearest case of a convention that varies. On the Brannock chart, a US men's 9 is a UK 8 1/2. By SATRA's examples it is a UK 8. Both are published by serious sources, so the result shows the Brannock reading first and the other one next to it. Mondopoint has a similar wrinkle: SATRA gives a UK men's 9 as Mondopoint 270, while the Brannock UK 9 fits a foot of about 267 mm, and the nearest 5 mm step to that is 265.

Brands add their own layer. Brannock's chart carries the note that variations exist within the same scale from one country to another, and width names like narrow or wide are, in Brannock's words, not standardized. Use the converter to find where you sit on each scale, then confirm with the brand's own size chart.

Kids' shoe sizes

Children's sizes in the UK and the US run from 0 to 13 and then start again at 1 for adult sizes, according to SATRA, which also notes that nobody knows for sure why the scale stops at 13. We found no freely readable standard that defines children's sizes by foot length, and Brannock's junior measuring device builds in about one size for growth. So this converter covers adult sizes for men and women only. For kids, measure the foot the same way and read the brand's own kids' chart.

Shoe size chart by foot length

US men's whole sizes on the Brannock scale with the foot length they fit and the matching readings on the other scales. EU is shown to one decimal because it falls between whole sizes. Use the converter above for half sizes.

How to use the shoe size converter

1. 1Measure your foot standing, from the heel to the tip of the longest toe, on both feet. Enter the longer one in inches or centimeters. Or choose A size I know and enter a size you wear.
2. 2Choose whether men's or women's sizes should come first. The result lists US men's, US women's, UK, EU and Mondopoint with the exact reading on each scale.
3. 3If a reading sits between two sizes, compare with the brand's chart, which may round differently. Copy the result or a link to keep it.

Sources

• The diversity of footwear sizing systems, SATRA Bulletin, December 2023: barleycorn and 1/3 inch steps, Paris point of 2/3 cm, Mondopoint in 5 mm steps, children's sizes 0 to 13, and the examples US men's 12 = UK 11, UK women's 5 = US women's 7, UK women's 8 = EU 42 and UK men's 9 = Mondopoint 270.
• Brannock Device history, The Brannock Device Co.: men's size 1 is 7 2/3 inches, each size 1/3 inch longer.
• Size comparison chart of the Standard Model Brannock Device, 2015: positions of the US, UK and EU scales.
• Brannock instructions and fitting tips: measuring standing, longest toe, both feet, width terms, junior model.
• BS ISO 9407:2019 Footwear sizing, Mondopoint system of sizing and marking, BSI product summary.
• NIST Special Publication 811, Appendix B.8: 1 inch = 2.54 cm exactly.

Built by Tobias Kurth, designer. Updated October 13, 2026.

Frequently asked questions