Convert shoe sizes between US men's and women's, UK, EU, India, Japan and Mondopoint via foot length, using the ISO/TS 19407 formulas.
By AdminDrafted with AI writing toolsUpdated Checked examples: 5
US men's 10 fits a foot about 270.9 mm long; the nearest EU (Paris points) size that isn't smaller is 43.
Formulas from ISO/TS 19407 (adult sizes); each already includes the standard allowance between foot and last.
ISO/TS 19407 rounds converted sizes up to the next size (here in steps of 0.5), for comfort.
Adult shoe sizes in the US men's, US women's, UK, Indian, EU, Japanese and Mondopoint systems all map to a foot length. The converter turns a size into a foot length L in millimetres with the ISO/TS 19407 formulas, then reads it on the target scale: EU = 3L/20 + 2 and UK = 3L/25.4 − 23, with US men's one size above UK and US women's two above.
Use it when buying shoes labelled in another country's system. The default, US men's 10, corresponds to a 270.9 mm foot, which is EU 42.6 before rounding and EU 43 after. Converted sizes round up to the next half size (5 mm steps for Japan and Mondopoint), as the specification recommends, so the answer errs towards room rather than a tight fit.
Brands cut their lasts differently, so compare the result with the brand's own foot-length chart. The formulas cover adult feet from 200 to 340 mm; children's sizes follow different formulas.
In the formulas, US_m denotes US men's sizes and US_w denotes US women's sizes on the FIA scale. L is foot length in millimetres.
Convert through foot length. In the ISO/TS 19407 adult formulas, US men's size n means a foot of (n + 22) × 25.4 ÷ 3 mm, and EU size = 3 × foot length ÷ 20 + 2, rounded up to a half size. US men's 10 is a 270.9 mm foot, EU 42.64, so EU 43.
Each system counts the same foot length L, in millimeters, in its own steps:
The formulas come from ISO/TS 19407:2015, which ISO has withdrawn in favor of ISO 19407:2023. The sizes below follow the 2015 formulas, which already include the allowance between the foot and the shoe's last.
The same foot is exactly UK 9 and US women's 11. Japan's 27.09 cm rounds up to 27.5, and Mondopoint rounds up to 275 because it moves in 5 mm steps.
Rows follow the ISO/TS 19407:2015 adult formulas, rounded up to the next half size, with US women's on the FIA scale. Brands cut their lasts differently, so treat each row as a starting point, not a fit guarantee.
| Size | From | To | Converted label |
|---|---|---|---|
| 10 | US men's | EU | 43 |
| 42 | EU | UK | 8.5 |
| 250 | Mondopoint (mm) | EU | 39.5 |
| 12 | UK | EU | 46.5 |
| 26.5 | Japan (cm) | US men's | 9.5 |
| 9 | US women's (FIA) | US men's | 8 |
A UK size spans 1.27 EU sizes, and no adult UK size lands exactly on an EU half size, so every conversion between the two falls between sizes.
The result rounds up, toward room rather than a tight fit. EU 42 is a 266.67 mm foot, which is UK 8.496, so it becomes UK 8.5.
Rounding also makes round trips drift. US men's 10 converts to EU 43, but EU 43 is a 273.33 mm foot, which converts back to US men's 10.28 and rounds up to 10.5. Convert from the label on the shoe you own, not from an earlier conversion.
On the FIA scale, women's sizes are men's plus 1, so a women's 9 is a men's 8. Many US brands use the common scale instead, where women's sizes are men's plus 1.5 and a women's 9 is a men's 7.5. Check which scale the brand's own chart uses.
UK sizes are nominally the same for men and women, although some manufacturers number women's UK sizes differently.
Japanese and Mondopoint sizes are the foot length itself, so a measured foot is the most direct starting point. Measure from the back of the heel to the tip of the longest toe, then compare the length with the brand's own foot-length chart.
Under these formulas a 265 mm foot is Japan 26.5, EU 42 and US men's 9.5. They cover adult feet from 200 to 340 mm, EU 32 to 53; children's sizes use different formulas.
The length converter turns a foot length in inches into millimeters. For garments, use the clothing size converter.
Checked against: Wikipedia ISO/TS 19407 adult table: US men 10 = UK 9 = US women 11 at 270.9 mm; the next sizes at or above that length are EUR 43 (273.3 mm) and Mondopoint 275
Checked against: Wikipedia ISO/TS 19407 table: EUR 42 = 266.7 mm, where UK 8.5 / US men 9.5 sit; FIA women's scale = men's + 1
Checked against: Wikipedia ISO/TS 19407 table: 250.0 mm row lists Mondopoint 250 and EUR 39.5; UK 6.5 is 249.8 mm, so the next UK size up is 7 (254.0 mm)
Checked against: Wikipedia ISO/TS 19407 table: UK 12 = 296.3 mm; EUR 46.5 = 296.7 mm is the next size up
EU 43. Under ISO/TS 19407, US men's 10 fits a 270.9 mm foot, which works out to EU 42.6; converted sizes are rounded up to the next half size, giving 43. The same foot is UK 9, India 9, US women's 11, Japan 27.5 cm and Mondopoint 275.
Subtract 1 on the FIA (Footwear Industries of America) scale used here: US women's 9 is US men's 8. Many US brands use the common scale instead, where women's sizes are men's plus 1.5, so women's 9 is men's 7.5. UK sizing is nominally the same for men and women, although some manufacturers number women's UK sizes differently.
They count in different units. One EU size is a Paris point, 2/3 cm (6.67 mm) of shoe length; one UK or US size is a barleycorn, 1/3 inch (8.47 mm). A full UK size therefore spans 1.27 EU sizes, and no adult UK size falls exactly on a whole or half EU size, so every conversion between the two rounds.
Mondopoint (ISO 9407) describes shoe size by foot length in millimetres, so a 270 mm foot is Mondopoint 270. Japanese-style centimetre labels express that as 27 cm. When comparing labels from China, Russia or South Korea, check the actual unit and brand chart instead of assuming a universal retail convention. Metric foot-length labels can also appear on ski boots, skates, pointe shoes and NATO military footwear.
In this converter, adult India and UK labels use the same common barleycorn-based model. UK-style labels may also be encountered in Ireland, Pakistan and South Africa; check the brand chart rather than assuming every product follows them. In this model, India 9 is UK 9 and US men’s 10. Mondopoint is available as an optional second comparison for India and the UK.
This calculator includes 5 worked examples with independently sourced answers. They run in the test suite, and you can run them here too.