Free Shoe Size Calculator (+ Guide)

What is a shoe size calculator?

A shoe size calculator turns your foot length into shoe sizes. Shoe sizes started from the length of the last, the shoe's inner form, and each country counts it differently.

These are the usual rules of thumb from foot length. They get you to the right size or within half a size.

How to measure your foot

You need a sheet of paper, a wall and a ruler.

Measure in the evening, with the socks you'll wear, since feet swell a little through the day.

A worked example

Here's the example the calculator loads when you press Try an example: a foot 27 cm long, or 10.6 inches.

US men's: 3 × 10.63 − 22 = 9.9, so a 10. US women's is 1 more, an 11. UK: 3 × 10.63 − 23 = 8.9, a 9. EU: 1.5 × 27 + 2 = 42.5.

Japan's size is 27, and Mondopoint 270.

Why brands differ

The rules of thumb are a starting point, and each brand builds its own lasts.

Running shoes run small

Many runners go up half a size for room as feet swell on a long run.

Boots and dress shoes run big

They're often cut longer, and thick socks change the fit.

Width matters too

A narrow or wide foot can need a different length in a brand that only makes one width.

Mistakes to avoid

These are the ways an online shoe order goes wrong.

• Measuring 1 foot when the other is longer
• Measuring in the morning, before feet swell
• Assuming US men's and women's sizes are the same
• Trusting a size from 1 brand for another

Already know your size in one country? The shoe size converter turns it into the others.

Who is the shoe size calculator for?

It's for anyone buying shoes online or abroad, and these tools help around it.

• Shoe size converter – for a size you already know
• Ring size calculator – for a ring that fits
• Running pace calculator – for what to train in your new shoes
• Currency converter – for a price in your money
• Discount calculator – for the price after a sale

Measure your foot once, and every chart becomes easy to read.