# How do I convert my shoe size?

Converts an adult shoe size between US women's, US men's, UK, and EU sizes and foot length, from the standard size formulas.

- Page: https://www.acalculator.org/convert/shoe-size
- JSON spec: https://www.acalculator.org/convert/shoe-size.json
- Version: 2b2b39893ba8

## Default answer

Example with the default inputs (Size system US women's, Size 8, US women's scale Men's + 1½ (common)): US women's 8 is US men's 6.5.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| from | Size system | The scale your size is in. |
| size | Size | Your shoe size on that scale, or your foot length in cm. |
| scale | US women's scale | How US women's sizes relate to US men's sizes. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| converted | Converted size | The US men's size, or the US women's size when you start from US men's. |
| usMen | US men's | The US men's size, rounded up to a half size. |
| usWomen | US women's | The US women's size, rounded up to a half size. |
| uk | UK | The UK size, rounded up to a half size. |
| eu | EU | The EU (Paris point) size, rounded up to a half size. |
| footCm | Foot length (cm) | The foot length the size fits, heel to longest toe. |
| footIn | Foot length (in) | The same foot length in inches. |
| mondopoint | Mondopoint (mm) | The ISO 9407 size: foot length in mm, rounded up to 5 mm. |

## Method

foot length L (mm) from your size; UK = 3 × L ÷ 25.4 − 23; US men’s = UK + 1; US women’s = US men’s + 1½; EU = 3 × L ÷ 20 + 2

## Assumptions

- Adult sizes only: UK 0 to 20. Children’s sizes use other zero points.
- UK sizes count barleycorns (1/3 inch) and EU sizes count Paris points (2/3 cm) of shoe last length. The last is taken as 2 sizes longer than the foot, as in ISO/TS 19407.
- US men's = UK + 1. US women's = US men's + 1½ on the common scale, or + 1 on the FIA scale.
- Every size is rounded up to the next half size, and Mondopoint up to the next 5 mm, because a shoe a little too big fits and one too small does not.
- Brands and countries differ by up to a size. Check the brand’s own chart, or measure your foot and compare foot lengths.

## Worked examples

1. from = us-women, size = 8, scale = common gives converted = US men's 6.5, usMen = 6.5, uk = 5.5, eu = 38.5, footCm = 24.13, footIn = 9.5, mondopoint = 245. Source: ISO/TS 19407:2015 sizing conversion (https://www.iso.org/standard/62349.html).
2. from = us-men, size = 10, scale = common gives converted = US women's 11.5, uk = 9, eu = 43, footCm = 27.093333, mondopoint = 275.
3. from = eu, size = 42, scale = common gives usMen = 9.5, usWomen = 11, uk = 8.5, eu = 42, footCm = 26.666667, mondopoint = 270.
4. from = us-women, size = 8, scale = fia gives usMen = 7, uk = 6, eu = 39, mondopoint = 250.
5. from = cm, size = 24, scale = common gives usMen = 6.5, usWomen = 8, uk = 5.5, eu = 38, mondopoint = 240.

## FAQ

### How do I convert women's to men's shoe sizes?

Subtract 1½. A US women's 8 is a US men's 6.5, and a women's 10 is a men's 8.5. Some makers use the older FIA scale, where the gap is 1 size; pick it under More options.

### How do I convert men's to women's shoe sizes?

Add 1½. A US men's 9 is a US women's 10.5. On the FIA scale, add 1.

### How do UK and US sizes compare?

A US men's size is 1 more than the UK size, and a US women's size is 2½ more (2 on the FIA scale). So a UK 7 is a US men's 8 and a US women's 9.5.

### How are EU sizes worked out?

An EU size counts Paris points (2/3 cm) of shoe length. With the usual allowance of 2 sizes over the foot, EU size = 3 × foot length in mm ÷ 20 + 2. A 26 cm foot is EU 41.

### Why does my size differ between brands?

The scales are old conventions, not a strict standard, and each maker picks its own lasts and allowances. Sizes can differ by half a size or more. For the best fit, measure your foot and use the brand's own chart.

### How do I measure my foot length?

Stand on a sheet of paper with your heel against a wall, mark the tip of your longest toe, and measure from the wall to the mark. Measure both feet in the evening and use the longer one.

## Sources

- ISO/TS 19407:2015, Footwear — Sizing — Conversion of sizing systems (https://www.iso.org/standard/62349.html): EU = 3/20 × L + 2 and UK = 3/25.4 × L − 23 for foot length L in mm, as quoted in Wikipedia, "Shoe size", section "ISO 19407 and shoe size conversion". https://en.wikipedia.org/wiki/Shoe_size
- Wikipedia, "Shoe size", section "United States": US men's = 3 × last length (in) − 24, one more than UK; women's sizes are men's plus 1½ (common scale) or plus 1 (FIA scale). https://en.wikipedia.org/wiki/Shoe_size
- ISO 9407:2019, Footwear sizing — Mondopoint system of sizing and marking: size is foot length in mm. https://www.iso.org/standard/71594.html