Shoe Size Converter
Convert a foot length or a shoe size between US, UK, EU and Mondopoint sizes using the ISO 19407 conversion, with the nearest size and the sizes either side.
Result
US size: about 9½Estimate
Sizes follow the ISO 19407 conversion; brands grade their own lasts, so try the neighbouring size too.
- UK size
- about 8½Estimate
- EU size
- about 42Estimate
- Mondopoint
- about 265Estimate
- Foot length
- 10.5 in (266.7 mm)
- Between standard sizes
- Yes: between standard sizes on the US, UK, EU and Mondopoint scalesEstimate
- Neighbouring sizes
- US 9 or 10; UK 8 or 9; EU 41½ or 42½; Mondopoint 260 or 270Estimate
https://calcgallery.com/size-conversions/shoe-size-converter-calculator/
Unit conversions follow from exact definitions and published notation rules. Sizes follow published standards and are approximate: makers grade their own, so check their chart. Figures are rounded only for display. Read the full disclaimer
How to use the Shoe Size Converter
- Measure your foot at the end of the day, standing, from the back of the heel to the tip of the longest toe. Measure both feet and use the longer.
- Choose whether you are entering that foot length or a size you already wear, and whether the shoes are men's or women's.
- Read the nearest US, UK, EU and Mondopoint sizes, and the sizes either side, then try the brand's own chart if it has one.
How shoe sizes work
Each national system counts steps of a fixed length along the foot or the shoe. The steps differ, and so do the starting points:
| System | One size | Starts at |
|---|---|---|
| Mondopoint | 5 mm of foot | zero; the size is the foot length in mm |
| EU (Paris) | 6.67 mm | zero |
| UK | 8.47 mm | 4 in, with 13 children’s sizes before adult 1 |
| US | 8.47 mm | the UK scale plus one size (men) or two (women) |
ISO 19407 aligns them all on foot length. UK and EU sizes were first defined on the length of the last, the form a shoe is made on, which is longer than the foot. The standard takes that difference as two sizes of the scale concerned, so:
UK = (foot length + 2 × 8.47 mm) ÷ 8.47 mm − 25EU = (foot length + 2 × 6.67 mm) ÷ 6.67 mmUS = UK + 1 (men), UK + 2 (women)The 25 is 12 steps from zero to the 4 inch start, plus the 13 children’s sizes. Because the steps differ, the systems only meet exactly by coincidence, which is why a result is shown as the nearest half size with the sizes on either side of it.
Measuring your foot
This is the step that decides whether the result is any use. Feet swell during the day and flatten under your weight, so measure late in the day, standing, not sitting. Put your heel against a wall and mark the end of the longest toe. Measure both feet: the two often differ, and the shoe has to fit the longer one. Wear the kind of sock you will wear with the shoes.
A shoe is made to fit a band of foot lengths, about half a size either side of its nominal length, so a measurement between two sizes is normal: try both neighbours. A foot exactly halfway is given the larger size, since a shoe slightly long can be worn and one slightly short cannot. Width matters as much as length.
What this page does not cover
Children’s shoes are left out. ISO 19407 sizes them with a different allowance, 8 % of the foot length rather than two sizes, and its children’s conversion table is not publicly available, so the page does not stretch the adult formula to cover them. The adult scales here run from UK 2 to 15 and EU 34 to 50, the range of the standard’s own table; a foot outside it is reported as smaller or larger than the end of the scale.
Width is not converted either. Mondopoint can carry a foot width in millimetres, but ISO 19407 converts length only, so the US and UK width fittings have no standard conversion to offer here.
With your numbers
- Mondopoint = foot length in mm = 266.7
- UK = (266.7 + 2 × 8.47) ÷ 8.47 − 25 = 8.49
- EU = (266.7 + 2 × 6.67) ÷ 6.67 = 41.99
- US men = UK + 1 = 9.49
Quick reference
Sizes follow the ISO 19407 conversion; brands grade their own lasts, so try the neighbouring size too.
| Example | Result |
|---|---|
| 250 mm foot, men | US size: about 7½ |
| 270 mm foot, men | US size: about 10 |
| 285 mm foot, men | US size: about 11½ |
| 9.5 in foot, women | US size: about 7½ |
| US men 10 | UK size: 9 |
| US women 8 | UK size: 6 |
| UK 8 | US size: 9 |
| EU 38 | US size: about 7½ |
Where the numbers come from
The fixed figures this calculator relies on, and the published source each one was checked against. How the calculators are built and checked
7 sources
ISO 19407:2023 Footwear - Sizing - Conversion of sizing systems, clause 4.2 c) and d): size grading interval 8,47 mm. Read in the iTeh Standards preview of the whole of clause 4 and Tables 1 and 2, https://cdn.standards.iteh.ai/samples/83106/d07404c4034c4b9495d8cc6dee3c5c48/ISO-19407-2023.pdf
Used for
- Length of one UK (and US) shoe size step, measured along the foot.
ISO 19407:2023 clause 4.2, the UK adult size formula and its key "25 = 12 sizes plus 13 children sizes". iTeh Standards preview of ISO 19407:2023, as for shoe.ukGradingInterval.
Used for
- Steps below UK adult size 0: 12 steps to the 4 in (101.6 mm) zero, plus the 13 children’s sizes.
ISO 19407:2023 clause 4.2 b): size grading interval 6,67 mm, starting at zero. iTeh Standards preview of ISO 19407:2023, as for shoe.ukGradingInterval.
Used for
- Length of one EU (Paris point) shoe size step, starting at zero.
ISO 19407:2023 clause 4.2, after the formulas: "empirically equivalent to two sizes" (two UK or two EUR sizes). Adults only; clause 4.4 gives 8 % for children. iTeh Standards preview of ISO 19407:2023, as for shoe.ukGradingInterval.
Used for
- Difference between foot length and shoe or last length, in size steps of the scale concerned.
ISO 19407:2023 clause 4.2 d): the US system corresponds to UK with an arbitrary off-set of one size for men; Table 2 applies it exactly. iTeh Standards preview of ISO 19407:2023, as for shoe.ukGradingInterval.
Used for
- US men’s size minus UK size.
ISO 19407:2023 clause 4.2 d): "usually two sizes difference for women’s footwear"; Table 2 applies exactly +2 in every row. iTeh Standards preview of ISO 19407:2023, as for shoe.ukGradingInterval.
Used for
- US women’s size minus UK size.
ISO 19407:2023 clause 4.2 a), citing DIN 66074-2:1975 Range 1; ISO 9407:2019 introduction gives 5 mm as the normal interval. ISO 9407 preview, https://cdn.standards.iteh.ai/samples/71594/d598a540c28541a9b6035aee81bd965f/ISO-9407-2019.pdf
Used for
- Mondopoint size step: foot length in whole 5 mm steps (Range 1).
Common questions about the Shoe Size Converter
- What is my EU shoe size?
- Measure your foot and enter the length: the EU size is (foot length + 2 × 6.67 mm) ÷ 6.67 mm, to the nearest half size. Converting from a UK or US size works too, but the foot length gives the more reliable answer because it skips the rounding already built into the size you wear.
- Why do shoe sizes differ between brands?
- A size names a last, the form the shoe is built on, and each maker shapes and grades its own lasts. The toe shape, the style and the material all change how much room there is in front of the toes, so two shoes marked with the same size can fit differently. The conversion here tells you where to start, not what will fit.
- How do I measure my foot for shoes?
- Stand with your weight on both feet, barefoot or in thin socks, heel against a wall, and mark the tip of the longest toe, which is not always the big toe. Measure the straight distance from the wall. Do it late in the day, when feet are at their largest, and use the longer foot.
- What is Mondopoint?
- The international shoe size of ISO 9407: the length of the foot in millimetres, usually in 5 mm steps, sometimes with the foot width after a slash. ISO 19407 notes that China, Japan and Korea size shoes by it. It is the only system that names the foot rather than the shoe.
- Why is UK 8 not EU 42 here?
- Many shoes are labelled UK 8 / EU 42, but the conversion in ISO 19407 puts UK 8 at EU 41½ and UK 4 at EU 36½, and the standard notes that it considers its own figures the more accurate. The two systems use different step lengths, so they can never line up at every size.