Shoe size conversion: US, UK, EU and Japan — and why it varies

Buying shoes online from another country means translating a size you know into one you do not. Conversion charts help, but they disagree with each other — and with the shoes. Knowing how the systems work explains why, and what to do about it.

How each system works

Every shoe-size system is a scale laid over the length of a foot, with its own starting point and step:

• UK and US sizes go up in steps of a third of an inch. US men's sizes run about one size above UK sizes, and US women's about one size above US men's.
• European (Paris point) sizes go up in steps of two-thirds of a centimetre.
• Japanese sizes and Mondopoint simply state the foot length in centimetres or millimetres.

UK, European, Japanese and Mondopoint sizes are the same for everyone; only US sizes have separate men's and women's scales.

The relationships

With L as foot length, the standard relationships are:

• UK ≈ 3 × L (inches) − 23
• US men's ≈ 3 × L (inches) − 22
• US women's ≈ 3 × L (inches) − 21
• EU ≈ 1.5 × L (cm) + 2

For a 27 cm foot (10.63 inches): UK about 9, US men's about 10, US women's about 11, EU about 42.5 and Japan 27. The Shoe Size Converter uses these relationships and rounds to the nearest half size.

Measure your foot

1. Stand on a sheet of paper with your heel against a wall.
2. Mark the tip of your longest toe — not always the big toe.
3. Measure from the wall to the mark in centimetres or inches.
4. Measure both feet in the evening, when feet are largest, and use the longer one.

The converter accepts a foot length directly. Foot length is also the most reliable number to compare with a brand's own chart.

Why brands disagree

Each maker builds shoes around its own last — the foot-shaped form a shoe is made on — and adds its own allowance for toe room. Some brand charts sit a full size away from the standard relationships. Running shoes are often cut differently from formal shoes from the same brand. That is why the same person can wear three different sizes from three makers.

Buying shoes in another system

• Find the brand's own size chart and compare your measured foot length with it.
• Read reviews for notes on whether the shoe runs large or small.
• Between sizes, choose the larger for walking and running shoes and thick socks.
• Check the returns policy before ordering from another country.

Children's sizes

Children's scales start from different points in each country and are not described by the adult relationships above. Measure the child's foot and use the brand's children's chart, leaving room to grow.

For other length conversions — centimetres to inches for a foot measurement, for example — the Length Converter converts exactly.