What is a Shoe Size Converter?
The shoe size converter translates foot length (mm) into US, UK, and EU sizing. It is useful for overseas purchases and comparing sizes across brands.
How it's calculated
Some countries (like Japan and Korea) use foot length in millimeters directly as the size — a 250mm foot is simply size 250.
Units that are easy to mix up
| Units | Why it's confusing | How to tell them apart |
|---|---|---|
| US men's vs women's sizing | Same foot length, different numbers | For the same foot, the women's size number reads about 1.5 higher than men's |
| US vs UK sizing | Same unit family, different starting point | UK sizes typically read 0.5 to 1 size smaller than US for the same foot |
Why does every country have a different system?
EU sizing is based on the Paris Point (about 6.67mm per size), while US/UK sizing is based on the barleycorn (1/3 inch per size), a unit dating back to 14th-century England where three barleycorns end-to-end equaled one inch. US and UK use the same unit but start counting from different points, which is why UK sizes typically read 0.5 to 1 size smaller than US for the same foot.
Good to know
- US sizing differs by gender — for the same foot length, the women's size number is typically about 1.5 higher than the men's.
- Foot width matters as much as length for fit, and it's a major reason certain brands' shoes can feel narrow on some wearers even when the length is correct.
- Feet actually swell throughout the day, growing up to about 5% larger by evening from standing and walking — which is why trying shoes on later in the day is generally recommended.
- Most people's two feet are slightly different sizes, typically by about 5mm, and shoes should be sized to the larger foot.
- Even within the same brand, sizing can vary by product line — a size 9 running shoe and a size 9 basketball shoe from the same company may not fit identically.
Frequently asked questions
Q. What US size is a 260mm foot?
Roughly US men's 8 or US women's 9.5, though this varies by brand — check the brand's specific size chart.
Q. Which is bigger, US or UK sizing?
For the same foot, the UK number is typically smaller than the US number, usually by 0.5 to 1 size.
Q. Should I size up if I'm between sizes?
A common rule of thumb is to leave 5–10mm of room beyond foot length, but checking brand-specific fit reviews is more reliable.