Shoe Size Converter

US, UK, EU, Japanese and centimetre shoe sizes, for men, women and children, converted through the one quantity that means anything physical: the length of your foot in millimetres, which is what ISO 9407 Mondopoint sizing actually is. Every other scale is a convention, and makers differ by up to a full size.

Last updated 24 Sep 2026

Shoe sizes

Any scale ⇄ foot length in mm

What do you have?

The size, or the length in mmRead in whatever the box above says. Measuring beats every chart: stand on paper against a wall in the evening, mark the longest toe, measure both feet and use the larger.

Fitting allowance (mm)How much longer the shoe’s last is than the foot. Two barleycorns, 16.93 mm or two thirds of an inch, is the classic English figure and is what makes the UK scale come out right against a maker’s chart. Raise it for a roomier fit.

Not a circuit: the foot length drawn to scale against a millimetre rule, because foot length is the one quantity in shoe sizing that means something physical. Every size number on the page is a convention sitting on top of this bar. The bar is drawn to the nearest 5 mm — the Mondopoint step of ISO 9407 — and the figures beside it are exact.

262.5mmExample

A US men’s size 9

The three scales, and the one measurement

last length = foot length + allowance · UK = 3 × last (in) − 25 · US men = UK + 1 · US women = UK + 2.5 · EU = 1.5 × last (cm) · JP = foot (cm) · Mondopoint = foot (mm)

barleycorn: 1/3 inch, 8.47 mm — one full UK or US size
Paris point: 2/3 cm, 6.67 mm — one full EU size, so EU steps are smaller than UK ones
allowance: how much longer the last is than the foot; two barleycorns (16.93 mm) is the classic English figure
Mondopoint: ISO 9407: the size IS the foot length in mm, in 5 mm steps (7.5 mm for safety footwear)
girth: Mondopoint and the Japanese system also carry a width or girth figure, which this page does not convert

Worked example

A US men's size 9
US men 9 is UK 8, because the US men's scale sits one barleycorn above the UK scale
UK 8 means a last of (8 + 25) ÷ 3 = 11.0 inches, which is 279.4 mm
Taking off the two-barleycorn allowance: 279.4 − 16.93 = 262.47 mm of foot
Mondopoint rounds that to 260; EU is 1.5 × 27.94 cm = 41.9, so size 42; Japan and the centimetre scale read 26.0
Clarks publishes UK 8 as 263 mm of foot length and EU 42 — half a millimetre and nothing at all from what this page computes

Clarks’ own chart against this page’s formula

Clarks states that its length column is actual foot length, heel to longest toe, which is what makes it usable as a check. The barleycorn formula reproduces its UK column to within 0.15 of a size at every one of these rows, and its EU column to within half an EU size. Clarks’ women’s chart carries the same UK number at the same foot length, which is the evidence that UK sizing has no men’s and women’s offset.
UK	EU (Clarks)	Foot length (mm, Clarks)	UK (this page)	EU (this page)
5.0	38.0	237	4.99	38.09
5.5	39.0	241	5.46	38.69
6.0	39.5	246	6.06	39.44
6.5	40.0	250	6.53	40.04
7.0	41.0	254	7.00	40.64
7.5	41.5	258	7.47	41.24
8.0	42.0	263	8.06	41.99
8.5	42.5	267	8.54	42.59
9.0	43.0	272	9.13	43.34
9.5	44.0	276	9.60	43.94
10.0	44.5	280	10.07	44.54
10.5	45.0	285	10.66	45.29
11.0	46.0	289	11.13	45.89
12.0	47.0	298	12.20	47.24
13.0	48.0	306	13.14	48.44
14.0	49.5	314	14.09	49.64

Why two charts disagree by half a size

Nike’s centimetre column runs 4 to 11 mm longer than Clarks’ foot length at the same UK size, because the two are not measuring the same thing — one is closer to the shoe, one is the foot. That gap is most of the reason retailer charts differ by half a size, and it is why the allowance on this page is an input rather than a buried constant.
US men (Nike)	UK (Nike)	EU (Nike)	Nike cm column (mm)	Clarks foot length at that UK size (mm)	Difference (mm)
7.0	6.0	40.0	250	246	4
8.0	7.0	41.0	260	254	6
9.0	8.0	42.5	270	263	7
10.0	9.0	44.0	280	272	8
11.0	10.0	45.0	290	280	10
12.0	11.0	46.0	300	289	11

The men’s and women’s offsets, as actually published

Only the US scale has a men’s and women’s offset, and it is 1.5 sizes. An older Footwear Industries of America formula makes it 1.0; charts built on that will read half a size low for women, which is a spread worth knowing about rather than a number worth arguing over.
Scale	Men’s and women’s relationship	Source
US	Women’s = men’s + 1.5 at every row	Nike, men’s and women’s charts
UK	No offset — the same number for the same foot	Clarks, men’s and women’s charts
EU	No offset — the scale is a last length in Paris points	Clarks, both charts
Mondopoint	No offset — the size is the foot length	ISO 9407
Japan	No offset — the size is the foot length in cm	Nike, Clarks

Measure the foot, then convert

Shoe sizes are not units. A UK 8 is not eight of anything you can measure; it is a position on a scale that counts barleycorns — a third of an inch, the length of a grain of barley — along the last the shoe was built on. The US scale counts the same barleycorns from a different starting point. The European scale counts Paris points of two thirds of a centimetre. Only one system on this page names a physical quantity, and that is Mondopoint, defined in ISO 9407: the size is the length of your foot in millimetres, in 5 mm steps, written alongside a width. The Japanese scale is the same idea in centimetres.

So measure. Stand on a sheet of paper with your heel against a wall, in the evening when your feet are at their largest, wearing the socks you mean to wear. Mark the end of the longest toe — which is not always the big toe. Do both feet, because most people have two different ones, and use the larger. That number, in millimetres, is the input this page most wants, and it is worth more than any conversion chart because it does not depend on anybody’s convention.

Where cross-gender conversion goes wrong. The US men’s and women’s scales are 1.5 sizes apart: a women’s 9 is a men’s 7.5. The UK and European scales have no such offset at all — Clarks publishes the same UK number against the same foot length in both its men’s and its women’s charts, and the European scale is a last length, which has no opinion about who is wearing it. So converting a women’s US size to a men’s US size means subtracting 1.5, and converting a women’s UK size to a men’s UK size means doing nothing. Charts that apply an offset to the UK column are wrong, and charts that omit it from the US column are wrong too.

The allowance is the fudge factor. A last is longer than the foot that goes in it, by about two barleycorns in the English tradition and about two to two and a half Paris points in the Continental one. That difference is not standardised, and it is where makers diverge: Nike’s centimetre column runs four to eleven millimetres longer than Clarks’ foot length at the same UK size, which is a good half of a size. That is why the allowance on this page is an input you can see and change rather than a constant buried in the code. Raise it for a roomier fit; lower it if you like a shoe close.

And then check the maker’s own chart. Sizing is a convention, not a standard, and a full size of disagreement between two brands is ordinary. Width matters as much as length and almost nothing converts it: Mondopoint and the Japanese system carry a girth figure, the UK trade uses letter fittings, the US trade uses B through EEEE, and none of them map onto each other. Use this page to get into the right two sizes, then use the shop. Sizing charts are conventions, not standards. Makers differ by up to a full size and the same maker differs between ranges, so treat this as a starting point and check the maker’s own chart before buying.

Frequently asked questions

What is a US men’s 9 in UK and EU sizes?

UK 8 and EU 42, for a foot of about 262 mm. Clarks publishes UK 8 as 263 mm and EU 42, so the three agree.

How do I convert a women’s US size to a men’s US size?

Subtract 1.5. A women’s 9 is a men’s 7.5. In UK and EU sizing there is nothing to subtract, because those scales are the same for both.

What is Mondopoint?

The sizing system defined in ISO 9407: the size is the mean foot length in millimetres, in 5 mm steps for ordinary footwear and 7.5 mm for safety footwear, usually printed with a width, as in 280/110. It is the only common system whose number is a measurement.

Is a Japanese size the same as a centimetre size?

Yes — both are the foot length in centimetres, so JP 26 and 26 cm are the same thing. Japanese sizes also carry a girth letter, which is a separate axis and does not convert.

How do I measure my foot properly?

Heel against a wall, standing, on paper, in the evening, in the socks you will wear. Mark the longest toe and measure to it. Do both feet and use the larger.

Why does the same size fit differently in two brands?

Because the size is a convention about the last, and the allowance between last and foot is not standardised. Two brands can differ by a full size, and the same brand can differ between ranges.

What are UK children’s sizes in adult sizes?

A UK children’s size is 13 numbers above the adult size for the same foot, so children’s 13½ runs straight into adult 1. The children’s scale starts at 0 for a foot of about 92 mm.

Related calculators

References

ISO 9407:2019, Footwear — Sizing — Mondopoint system of sizing and marking. Cited by number: the standard is copyrighted and its tables are not reproduced here. What this page uses is its definition — the size is the mean foot length in millimetres, in 5 mm steps for casual footwear and 7.5 mm for protective footwear, written as length/width.
Clarks, Shoe size chart and guide, clarks.com/en-gb/fitguide (read 26 September 2026). The length column is stated on the page to be actual foot length, heel to longest toe, which is what makes it usable as a check. Its men’s and women’s columns carry the same UK number at the same foot length — the evidence that UK sizing has no gender offset.
Nike, Men’s footwear and Women’s footwear size charts, nike.com/size-fit (read 26 September 2026). Used for the spread rather than for the conversion: Nike’s centimetre column runs about 6 mm longer than Clarks’ foot length at the same UK size, and Nike’s US women’s column is 2.5 sizes above its UK column at every row.
Wikipedia, Shoe size and Paris point (read 26 September 2026), for the barleycorn and Paris-point formulas and their sources: UK adult = 3 × last length (in) − 25, US men = 3 × last (in) − 24, EU = 3/2 × last length (cm), one barleycorn = 1/3 in, one Paris point = 2/3 cm.