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Shoe Size Converter

Convert adult shoe sizes between US men's, US women's, UK, EU and Japanese sizes, or find approximate sizes from a foot length.

Level: Grades 6–7

  • Common Core standard 6.EE.A.2.cEvaluate expressions at specific values of their variables. Include expressions that arise from formulas used in real-world problems. Perform arithmetic operations, including those involving whole-number exponents, in the conventional order when there are no parentheses to specify a particular order (Order of Operations).
Printable worksheet

Shoe Size Converter

Know the answer you need? Pick an input to work backward.

Inputs

Result

EU size

43

A foot about 27.1 cm long is roughly EU 43, US men's 10, US women's 11.5 and UK 9.

US men's size
10
US women's size
11.5
UK size
9
Japan / Mondopoint (foot length)
27 cm
Foot length
27.1 cm
Foot length in inches
10.67 in

See the step-by-step solution ↓

Step-by-step solution

  1. Foot length from a US men's size: (size + 22) ÷ 3 inches

    10+223=10.666667 in

  2. Each US size is a third of an inch, so US men's = 3 × foot length (in) − 22. Women's adds 1.5, and UK takes away 1

    3×10.666667−22=10

  3. EU = 1.5 × (foot length in cm + 1.6933 cm of extra room in the shoe)

    1.5×(27.093333+1.6933)=43.18

  4. Round the EU size to the nearest half size

    EU size=43

Test yourself

20 quick questions built from this calculator's formula: work out results, predict what happens when an input changes, and work backward from an answer. Every answer comes with the working.

What this calculator does

Find your shoe size in US, UK, European and Japanese sizes, from a size you know or your foot length. Shoe sizes look like simple numbers, but each system measures something different, in different steps. American and British sizes go up in thirds of an inch. European sizes go up in two-thirds of a centimetre. Japanese sizes are just the foot's length in centimetres. On top of that, US men's and women's sizes don't line up with each other.

This converter connects them all through foot length. Enter a size you know, or measure your foot, and it shows the closest match in each system. Every brand cuts its shoes a little differently. So use the result as a starting point, and check the maker's own chart when there is one.

Where it's used

Why this math matters outside the classroom:

  • Online shopping. A man with a 10.5 in foot gets 3 × 10.5 − 22 = 9.5 as an approximate US men's size.
  • Women's sizes. A US men's 8 is roughly a US women's 9.5, since the two scales are about 1.5 sizes apart.
  • Shopping abroad. Travelers convert their usual size to an approximate EU number before trying on shoes in Europe.
  • Japanese sizes. Japanese sizes give foot length in centimeters, so a 26 cm foot is about a size 26.
  • Evaluating a formula. Students evaluate 3L − 22 for several foot lengths and see that each extra inch adds 3 sizes.

Grade level and standards: Grades 6–7; Common Core State Standards for Mathematics 6.EE.A.2.c. © Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.

How to use it

  1. Choose what you know: a foot length, or a US men's, US women's, UK, EU or Japanese size.
  2. Enter the size, or the foot length in centimetres, inches or millimetres.
  3. Read the EU size and the other matching sizes, rounded to the nearest half size.
  4. When buying in another system, compare with the brand's size chart. Allow for socks and the style of shoe.

What the inputs mean

Foot length
Stand on a sheet of paper with your heel against a wall, and mark the tip of your longest toe. Measure from the wall to the mark. Measure both feet later in the day, and use the longer one.
US women's size
For the same foot, US women's sizes are usually 1.5 sizes above men's. So a women's 8 is about a men's 6.5.
Japanese size
Japanese sizes give the length of your foot in centimetres, not the length of the shoe. The international Mondopoint system works the same way.

Formula and method

US men's size = 3 × foot length (in) − 22
US women's size = US men's size + 1.5
UK size = US men's size − 1   (= 3 × foot length (in) − 23)
EU size = 1.5 × (foot length (cm) + 1.69 cm)
Japanese / Mondopoint = foot length (cm)

British and American sizes grow by a barleycorn, an old unit equal to one third of an inch, per size. That's why each formula multiplies the foot length in inches by 3. The fixed numbers (22 and 23) set where size zero falls. The UK adult scale sits one size below US men's.

European sizes count Paris points, which are two-thirds of a centimetre each. So the length is multiplied by 1.5. They measure the shoe's last, the foot-shaped form a shoe is built around. A last is a little longer than the foot, so about two-thirds of an inch (1.69 cm) is added first. The same extra room is built into the UK and US formulas.

These are the rules of thumb behind most published conversion tables. They aren't exact standards. Real tables from shoe makers can differ by half a size or more. Sports shoes, fashion shoes and work boots often fit differently too.

Worked example

A shopper who wears a US men's 10 is ordering from a European store.

  1. Foot length = (10 + 22) ÷ 3 = 10.67 in, or 10.67 × 2.54 = 27.09 cm.
  2. EU size = 1.5 × (27.09 + 1.69) = 43.18, which rounds to 43.
  3. UK size = 10 − 1 = 9. US women's = 10 + 1.5 = 11.5. Japanese ≈ 27 cm.

Result: A US men's 10 is about EU 43, UK 9, US women's 11.5 and Japanese 27.

Understanding the result

If the result falls between two European sizes, choose the larger one for boots or thick socks. Choose the smaller one for shoes meant to fit snugly, such as some climbing or cycling shoes.

The foot length is the most reliable number here. Many brands publish a chart by foot length in centimetres, which avoids the size-system problem completely.

Half a size is about 4 mm of length. A whole size is about 8.5 mm for US and UK sizes, and 6.7 mm for EU sizes.

Assumptions and limitations

  • Adult sizes only, using the common US, UK, EU and Japanese rules of thumb above.
  • The foot length is measured barefoot from the heel to the longest toe.
  • These are approximate. Brand charts can differ by up to a full size.
  • Children's and babies' sizes use different scales and aren't covered.
  • Width (such as narrow, D or wide fittings) isn't converted.
  • The range covers adult foot lengths from 21 to 32 cm.

Frequently asked questions

How do I convert women's shoe sizes to men's?

Take about 1.5 off the US women's size to get the US men's size for the same foot. So a women's 9 is roughly a men's 7.5. In UK and EU sizes, men's and women's scales are usually the same.

Is a UK size the same as a US size?

No. For the same foot, a UK adult size is usually about one number smaller than the US men's size. It's about 2.5 smaller than the US women's size. A UK 8 is roughly a US men's 9.

Why do my shoe sizes differ between brands?

Each maker designs its own lasts, the foot-shaped forms shoes are built around. Each also decides how much room to leave around the toes. The size number only sets the rough length, so the same number can fit differently.

How do I measure my foot for shoe size?

Stand on a sheet of paper with your heel against a wall. Mark the tip of your longest toe and measure the distance. Do it for both feet late in the day, when feet are slightly larger, and use the longer measurement.

How this calculator is checked

Method: Common shoe-size rules of thumb: barleycorn (1/3 in) UK and US scales with a 2/3 in last allowance, US women's = men's + 1.5, EU Paris point (2/3 cm) of last length, Japanese/Mondopoint foot length. The calculation is covered by automated tests with known reference values and edge cases. Last updated 2026-10-18. Found a problem? Tell us.

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