FairSole › Buying guides

Shoe size conversion: UK, EU and US sizes compared

Nesim Yılmaz · 09.11.2026

A UK 8 isn't the same length in every brand. If you buy online, knowing your foot length in centimetres saves a lot of returns.

Measure your feet

1. In the evening, wearing socks, stand on a sheet of paper against a wall.
2. Mark the tip of your longest toe and measure to the wall.
3. Measure both feet and use the larger number.
4. Add 0.5–1.5 cm of room depending on the shoe.

Size chart (guide values)

Typical differences

• Nike, Adidas, Puma: tend to run small; consider half a size up.
• Hoka, Asics: usually true to size.
• Birkenstock, Dr. Martens: whole sizes only; size down if unsure.
• Lowa, Meindl: generous; go by foot length plus 1–1.5 cm.

How much room should a shoe have?

Your foot length and the inside length of the shoe should never be the same. How much space you need in front of your toes depends on the shoe:

• Running shoes: about 1–1.5 cm, roughly a thumb's width. Your foot slides forward and swells when you run; without room you risk black toenails.
• Walking boots: about 1–1.5 cm. Your toes shouldn't hit the front on descents.
• Winter boots: about 1 cm with thick socks. Tight boots feel colder.
• Everyday trainers: about 0.5–1 cm.
• Sandals: your toes shouldn't hang over the sole; leave about half a centimetre front and back.

Why sizes differ between systems

UK and US sizes go up in steps of a third of an inch (about 8.5 mm), while EU sizes use the "Paris point" of two-thirds of a centimetre (about 6.7 mm). Because the steps don't line up, every conversion is rounded. On top of that, each brand decides how much extra length to build into its lasts, so a UK 8 can be half a centimetre longer in one brand than another.

UK half sizes and wide fittings

The UK is one of the few markets where many brands offer half sizes and lettered width fittings. Clarks, for example, sells many styles in several widths. If you have wide or narrow feet, it's worth looking for these before going up or down a size.

Children's shoes

Children's feet grow fast, so measure every three to four months. Buying two sizes up "to grow into" makes walking harder; the usual advice is about 1–1.5 cm extra over foot length.

Ordering online without returning half of it

• Compare your foot length in centimetres with the brand's own size chart rather than ordering your usual size.
• Read fit comments in reviews ("runs small", "runs large").
• Check the returns policy before you buy: time limit, cost and condition.
• Try shoes on indoors on a clean floor and keep the labels on.

On FairSole you can pick your size at the top of the page. We then only show deals that are in stock in your size.

Frequently asked questions

When is the best time to measure my feet?

In the evening. Feet swell slightly during the day and are at their largest by evening. A shoe bought in the morning can feel tight later.

My feet are different lengths – which one do I go by?

Always the longer foot. A few millimetres' difference is completely normal. For the smaller foot, a thicker sock or an insole can take up the space.

What EU size is a UK 8?

In most charts EU 42. Depending on the brand it can be EU 41.5 or 42.5. The safest way is to compare foot length in centimetres.

I'm between two sizes – which should I buy?

For running shoes, walking boots and winter boots, go for the larger size. For trainers and sandals, check reviews: if a model runs small, size up; if it runs large, size down.

How do I know a shoe is too narrow?

If the length is right but it pinches at the sides. Going up a size won't fix it – the shoe just gets longer. Look for wide fittings instead; see our guide to shoes for wide feet.

Are US men's and women's sizes the same?

No. For the same foot length, a US women's size is about 1.5 higher than a US men's size. Unisex shoes are usually sized in men's.