Shoe Size Conversion
Enter a size you already know — from any country — or measure your foot, and see the equivalent in US, UK, EU, Japan and China. Fill in one box only; everything else is worked out from it.
Each system rounds to its own step, so converting back and forth can land you a half-size away from where you started.
Your row is highlighted. Brands vary, so treat this as a starting point rather than a guarantee.
There is no world shoe size
Metres, kilograms and seconds have international definitions. Shoe sizes do not. What exists instead is a handful of national systems that grew up independently, each counting something slightly different, and none of them agreeing on where zero sits or how big a step is.
The reason is chronology. Cobblers were sizing shoes for individual feet centuries before anyone mass-produced them, and by the time factories arrived, every country already had its own habits, its own units and its own barleycorn-derived traditions. Standardising afterwards would have meant relabelling every last, every catalogue and every customer's expectation, which nobody had a reason to do.
So a conversion is always an estimate that passes through a common quantity — foot length — and comes out the other side rounded to whatever step the destination system uses. It gets you close. It cannot be exact, because the systems are not measuring the same thing to begin with.
What each country's number actually counts
Once you see what each system is counting, the whole thing stops being mysterious.
US women = 3L − 21 (L in inches, half steps)
US men = 3L − 22 (L in inches, half steps)
UK/India = 3L − 23 (L in inches, half steps)
EU = 1.5 × cm + 2 (whole steps)
Japan = cm (half steps)
China = 2 × cm − 10 (whole steps)
Worked through for a 10-inch foot (25.4 cm)
US women = 30 − 21 = 9 US men = 30 − 22 = 8
UK = 30 − 23 = 7 EU = 38.1 + 2 = 40
Japan = 25.4 → 25.5 China = 50.8 − 10 = 41
The three-per-inch pattern in the US and UK numbers is a leftover from the barleycorn, an old English unit of a third of an inch. That is why those sizes step by a third of an inch and why a half size is a sixth of an inch — about four millimetres, which is far less than the difference between two brands.
Japan is the honest one: the number is simply your foot length in centimetres. This system, sometimes called Mondopoint, is also what ski boots and skates use, and it is the only one where the label tells you something directly measurable.
Note that US men and US women differ by exactly one, which is why the familiar rule of thumb — women's size minus one gives men's — works. UK sits one below US men for the same reason.
Measuring your foot properly
Every number on this page comes from one measurement, so it is worth taking that measurement well.
Stand on a sheet of paper against a wall with your heel touching it, and mark the end of your longest toe — which is not always the big one. Do it standing rather than sitting, because a foot lengthens under body weight. Wear the socks you would wear with the shoes. Measure both feet and use the larger; most people have a noticeable difference between them.
Measure late in the day. Feet swell over the course of a day and can be several millimetres longer by evening than they were at breakfast, which is enough to move you a half size. A shoe fitted to a morning foot can be uncomfortable by the afternoon.
Why converting back does not return you
Convert a US 9 to EU and back and you may not land on 9 again. That is not a bug in the arithmetic; it is what happens when systems with different step sizes are chained together.
US and UK sizes step by a third of an inch, Japan by five millimetres, EU and China by a whole unit. Each conversion rounds to the destination's step, and that rounding is not reversible. Going out and back can leave you a half size from where you started, and the error is largest when hopping between systems whose steps do not divide evenly into each other.
The practical response is to convert once, from the number you actually know, rather than chaining. If you know your foot length in centimetres, enter that — it is the cleanest starting point because every system is derived from it directly rather than through another country's rounding.
Children's sizes restart
Children's sizing has a quirk that catches people out: the numbers run up to about 13 and then start again at 1. A child's 13 and a child's 1 are adjacent sizes, roughly four millimetres apart, not twelve sizes apart.
That is why this calculator asks which age group you are converting for. The infant and toddler run and the older children's run use different intercepts, and the same foot length produces a different label depending on which run it falls in. Ask for a size beyond the top of the infant scale and the honest answer is that it is off that scale entirely, not a larger number.
Children's feet also grow fast — often a size every few months in the early years — so a measurement goes stale quickly. Buying a little large is normal practice, but a shoe that is too long changes how a child walks, so there is a limit to how far ahead it is sensible to buy.
Length is only half the fit
Everything here is derived from length, and length alone does not determine whether a shoe fits.
Width matters as much and is far less standardised. US brands sometimes offer letter widths, from narrow through to extra wide, but the letters do not mean the same thing across brands and most shoes are sold in one width only. Beyond width there is the shape of your arch, the height of your instep, the circumference around the ball of the foot, and how much room your toes need to splay.
Then there is the last — the form a shoe is built around. Two shoes from the same brand in the same stated size can fit differently if they are built on different lasts, and running shoes, dress shoes and boots routinely are. This is why the same person genuinely wears different sizes in different models, and why nothing on this page can replace putting the shoe on.
Buying from another country
A conversion table is most useful when you cannot try the shoe on, which is exactly when errors cost the most. A few things reduce the risk.
Prefer the retailer's own chart over a generic one. Many brands publish a foot-length measurement against each size they sell, and that is better information than any conversion, because it describes their lasts rather than a national average. If a listing gives a length in centimetres, use it and ignore the size label entirely.
Check the return terms before ordering, particularly for international purchases where return shipping can cost more than the discount that tempted you. And if you are between sizes, the larger one is usually the safer error: a shoe slightly too big can be managed with an insole or thicker socks, while one too short cannot be fixed at all.
Frequently asked questions
How do I convert my shoe size to another country's?
Work through foot length. Enter any size you know in the box for its system and everything else is derived from the length that implies — US women's is three times the length in inches minus 21, EU is one and a half times the length in centimetres plus 2, Japan is simply the length in centimetres. A 10-inch foot is a US women's 9, a US men's 8, a UK 7, an EU 40 and a Japanese 25.5.
What size is a US 8 in EU?
A US men's 8 works out at a 10-inch foot, which is an EU 40. A US women's 8 is a shorter foot, about 9.67 inches, which comes out at EU 39. The men's and women's scales differ by one full size, so it matters which one you mean.
Is UK the same as US shoe size?
No. UK sizes run one below US men's and about two below US women's for the same foot. A UK 7 is a US men's 8 and a US women's 9. The step size is the same in both systems — a third of an inch — so the gap stays constant across the range.
Why does converting back give me a different size?
Because each system rounds to its own step and rounding cannot be undone. US and UK step by a third of an inch, Japan by five millimetres, EU and China by whole units, so chaining conversions can leave you a half size from where you began. Convert once from the number you actually know rather than hopping between systems.
How should I measure my foot?
Stand on paper with your heel against a wall, mark the end of your longest toe, and measure the distance. Do it standing rather than sitting, wear your usual socks, measure both feet and use the larger, and do it late in the day when your feet are at their largest.
Why do children's sizes go back to 1?
Children's numbering runs to about 13 and then restarts, so a child's 13 and a child's 1 are neighbouring sizes rather than twelve apart. The infant and older children's runs use different starting points, which is why this calculator asks which age group you mean before converting.
Can I rely on a conversion instead of trying shoes on?
Only as a starting point. Conversions use length, but fit also depends on width, instep, arch and the last a shoe is built on, and none of those is standardised. The same person often wears different sizes in different models from the same brand. Where a retailer publishes a foot length for each size, that beats any conversion table.
These conversions are estimates derived from foot length using widely published formulas. There is no international shoe sizing standard, and manufacturers, brands and individual models differ from one another and from any general table, so the sizes shown here may not match a particular shoe. Use them as a starting point, check the retailer's own size chart where one is available, and try shoes on where you can. Learn more about how we build our calculators and read our privacy policy.