Shoe sizes come from old units: English sizes step by a barleycorn (⅓ in) and the European Paris point is ⅔ cm. That is why one UK or US size equals about 8.5 mm of foot length while one EU size is 6.7 mm. Fit also varies by brand and style, so use the result as a starting point.
How to use the Shoe Size Calculator
- I know
- Foot length
- Shoe size
Results update as you type, and every field accepts the units shown in its menu.
How it works
Choose what you know – your foot length or a size in one system – and enter it. Measure from the back of the heel to the tip of the longest toe while standing.
Tips
- Measure over thin clothing with a soft tape held snug but not tight, and keep the tape level all the way round.
- Take each measurement twice; if you are between sizes, the larger size is usually the safer choice.
- Size charts vary by brand and country – check the maker’s own chart when it is available.
- For sewing projects, pre-wash fabric before cutting and buy 10% extra for shrinkage, pattern matching and mistakes.
Common mistakes to avoid
- Mixing inches and centimetres between the tape and the size chart.
- Forgetting seam and hem allowances when cutting fabric.
- Measuring an old, stretched garment instead of your body.
Inputs explained
| Field | What to enter |
|---|---|
| I know | Choose one: My foot length, US men’s size, US women’s size, UK size … |
| Foot length | Units: cm, in, mm, m |
| Shoe size | A number |
What each result means
- US men’s = round((3×[Foot length]÷0.0254 – 22)×2)÷2
- US women’s = round((3×[Foot length]÷0.0254 – 21)×2)÷2
- UK = round((3×[Foot length]÷0.0254 – 23)×2)÷2
- EU = round(3.81×[Foot length]÷0.0254 + 2)
- Japan (cm) = round([Foot length]÷0.01×2)÷2
- Korea (mm) = 5×round([Foot length]÷0.001÷5)
- US children’s (if a child) = round((3×[Foot length]÷0.0254 – 9.67)×2)÷2
Example values
How the main result changes when Foot length changes and everything else stays at the example values above:
| Foot length (cm) | US men’s |
|---|---|
| 13.33 | -6 |
| 20 | 1.5 |
| 26.67 | 9.5 |
| 33.34 | 17.5 |
| 40 | 25 |
| 53.34 | 41 |
Formula
Foot length in inches L: US men = 3L − 22; US women = 3L − 21; UK = 3L − 23; US child = 3L − 9.67EU = 1.27 × (UK + 23) + 2 ≈ 3.81L + 2; Japan = foot length in cm; Korea = foot length in mmWorked example
Inputs — I know: My foot length; Foot length: 26.67 cm; Shoe size: 9.
Results — Foot length = 10.5 in; US men's = 9.5; US women's = 10.5; UK = 8.5; EU = 42; Japan (cm) = 26.5; Korea (mm) = 265; US children's (if a child) = 22.
Frequently asked questions
What size is a 10.5 inch foot?
About US men's 9.5, US women's 10.5, UK 8.5 and EU 42.
How do I convert US to EU shoe size?
Add about 33 to US men's sizes (US 9 ≈ EU 42) – but always check the brand's chart.
Should I measure in the evening?
Yes – feet swell during the day, so evening measurements avoid shoes that pinch.
What formula does the Shoe Size Calculator use?
Foot length in inches L: US men = 3L − 22; US women = 3L − 21; UK = 3L − 23; US child = 3L − 9.67.