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What is a shoe size converter?

A shoe size converter is a helpful tool that allows you to easily convert shoe sizes between various international sizing systems — such as US, UK, EU, JP (Japan), and KR (Korea). Since each region uses its own unique standards and measurement units for defining shoe sizes, it can be confusing to determine which size corresponds to another. For example, a men’s US size 9 is not the same as a UK size 9 or a European size 43.

The shoe size converter simplifies this process. By entering a single known shoe size or foot length, you can obtain corresponding sizes across global standards instantly. This tool is particularly useful when shopping online for footwear from international brands, traveling abroad, or buying shoes as gifts for others.

The calculator uses mathematical formulas based on length conversions (centimeters or inches) and size grading systems used by different regions. In this comprehensive article, you will learn how the conversions are calculated, what international differences exist, and how to apply them accurately.

The importance of understanding shoe size systems

Shoe sizing is not standardized globally, and manufacturers use different molds and measurement conventions. Understanding these differences is crucial for selecting comfortable footwear. Poorly fitting shoes can lead to blisters, foot pain, posture problems, and other health issues.

Each sizing system is tied to either:

  • Foot length (measurement of the actual foot), or
  • Last length (the length of the shoe mold used in production).

Furthermore, the unit of measurement differs:

  • Some systems use inches (like the UK and US).
  • Others use millimeters or centimeters (like the EU, JP, and KR systems).

The converter bridges all these methods, ensuring you always know the correct fit, regardless of the country.

Common international shoe size systems

1. United States (US)

The US shoe sizing system differentiates between men’s, women’s, and children’s sizes. The numerical difference between genders is typically one size (e.g., a US men’s 8 ≈ US women’s 9). Children’s sizes also follow specific scales that are not directly proportional to adult sizes.

2. United Kingdom (UK)

The UK sizes differ slightly from the US ones. A men’s UK 9 corresponds to a US men’s 10, roughly one size larger when converted. The UK uses the Barleycorn system, where each full size increases by 1/3 inch in foot length.

3. European Union (EU)

The EU sizing system uses the Paris point, where one unit equals 2/3 of a centimeter (6.67 mm). EU sizes are unisex and increase incrementally by equal steps.

4. Japan (JP)

Japanese shoe sizes are straightforward: they are measured entirely by foot length in centimeters. Hence, someone with a foot measuring 27 cm wears a Japanese size 27.

5. Korea (KR)

Similar to Japan, Korean sizes use millimeters as their measuring unit. A foot measuring 270 mm equals a Korean size 270.

Formula

The formulas linking foot length in inches to different global shoe sizes come from standardized measurement approximations. They allow precise and quick conversions.

  1. Convert millimeters to inches
inches=millimeters25.4\text{inches} = \frac{\text{millimeters}}{25.4}
  1. United States system

For men:

USmale=(3×inches)−22\text{US}_{\text{male}} = (3 \times \text{inches}) - 22

For women:

USfemale=(3×inches)−21\text{US}_{\text{female}} = (3 \times \text{inches}) - 21

For children:

USchild=(3×inches)−9.67\text{US}_{\text{child}} = (3 \times \text{inches}) - 9.67
  1. United Kingdom system

Adults:

UKsize=(3×inches)−23\text{UK}_{\text{size}} = (3 \times \text{inches}) - 23

Children:

UKchild=(3×inches)−10\text{UK}_{\text{child}} = (3 \times \text{inches}) - 10
  1. European Union system
EUsize=1.27×(UKsize+23)+2\text{EU}_{\text{size}} = 1.27 \times (\text{UK}_{\text{size}} + 23) + 2

Examples

Let’s compute different conversions step-by-step.

Example 1: Converting a 27 cm foot length for a man (US size)

Step 1: Convert centimeters to inches

27 cm=272.54=10.63 inches27 \text{ cm} = \frac{27}{2.54} = 10.63 \text{ inches}

Step 2: Apply the US men’s formula

USmale=(3×10.63)−22=31.89−22=9.89\text{US}_{\text{male}} = (3 \times 10.63) - 22 = 31.89 - 22 = 9.89

Result: US men’s size ≈ 10

Step 3: Find equivalent UK and EU sizes

UKsize=(3×10.63)−23=31.89−23=8.89⇒UK 9\text{UK}_{\text{size}} = (3 \times 10.63) - 23 = 31.89 - 23 = 8.89 \Rightarrow \text{UK 9} EUsize=1.27×(8.89+23)+2=1.27×31.89+2=40.5+2=42.5\text{EU}_{\text{size}} = 1.27 \times (8.89 + 23) + 2 = 1.27 \times 31.89 + 2 = 40.5 + 2 = 42.5

EU size ≈ 43

Hence, for a foot length of 27 cm:

  • US Men: 10
  • UK: 9
  • EU: 43

Example 2: Converting women’s foot length 24 cm

inches=242.54=9.45\text{inches} = \frac{24}{2.54} = 9.45

Now apply:

USfemale=(3×9.45)−21=28.35−21=7.35⇒US size 7.5\text{US}_{\text{female}} = (3 \times 9.45) - 21 = 28.35 - 21 = 7.35 \Rightarrow \text{US size 7.5} UKsize=(3×9.45)−23=28.35−23=5.35⇒UK size 5.5\text{UK}_{\text{size}} = (3 \times 9.45) - 23 = 28.35 - 23 = 5.35 \Rightarrow \text{UK size 5.5} EUsize=1.27×(5.35+23)+2=1.27×28.35+2=36.99+2=38.99⇒EU size 39\text{EU}_{\text{size}} = 1.27 \times (5.35 + 23) + 2 = 1.27 \times 28.35 + 2 = 36.99 + 2 = 38.99 \Rightarrow \text{EU size 39}

Thus, 24 cm = US 7.5 / UK 5.5 / EU 39 / JP 24 / KR 240

Example 3: Children’s size for 15 cm foot length

inches=152.54=5.91\text{inches} = \frac{15}{2.54} = 5.91

Apply the child formula:

USchild=(3×5.91)−9.67=17.73−9.67=8.06\text{US}_{\text{child}} = (3 \times 5.91) - 9.67 = 17.73 - 9.67 = 8.06

Rounded down: US size 8

Size charts

Children’s shoe size chart

Age (approximately)Foot Length (cm)Foot Length (in)EUUSUKJPKR
010.03.94172210.0100
3 months10.54.13182.52.510.5105
6 months11.04.3318.53.5311.0110
9 months12.04.72204.5412.0120
1 year13.05.1221.55.55.513.0130
1.5 years14.05.512376.514.0140
2 years15.05.9124.587.515.0150
3 years16.06.30269916.0160
4 years17.06.6927.510.51017.0170
5-6 years18.07.092911.511.518.0180
7-8 years19.07.4830.51312.519.0190
8-9 years20.07.87321413.520.0200
9-10 years21.08.2733.5151521.0210

Women’s shoe size chart

Foot Length (cm)Foot Length (in)EUUSUKJPKR
22.08.66355322.0220
22.58.86365.53.522.5225
23.09.0636.56423.0230
23.59.2537.57523.5235
24.09.45387.55.524.0240
24.59.65398624.5245
25.09.8439.58.56.525.0250
25.510.0440.59725.5255
26.010.24419.57.526.0260
26.510.434210.58.526.5265
27.010.6342.511927.0270
27.510.8343.511.59.527.5275
28.011.0244121028.0280

Men’s shoe size chart

Foot Length (cm)Foot Length (in)EUUSUKJPKR
24.59.65397624.5245
25.09.8439.57.56.525.0250
25.510.0440.58725.5255
26.010.24418.57.526.0260
26.510.43429.58.526.5265
27.010.6342.510927.0270
27.510.8343.510.59.527.5275
28.011.0244111028.0280
28.511.224511.510.528.5285
29.011.4245.512.511.529.0290
29.511.6246.5131229.5295
30.011.814713.512.530.0300

Notes

  • Shoe length (size) may differ slightly among brands due to manufacturing variances. Always check brand-specific size charts before purchasing.
  • Foot length should be measured at the end of the day when feet are at their largest.
  • Always allow about 0.5–1 cm additional length to ensure comfort.
  • For accurate measurement: place your foot on a sheet of paper, mark the longest toe and heel, measure the distance in centimeters, then find your corresponding size.

Frequently Asked Questions

How to measure your foot length correctly at home?

Place a piece of paper on the floor against a wall. Stand with your heel against the wall and trace around your foot. Measure the distance from your heel to the tip of your longest toe. This gives your foot length, which can be converted to shoe size using the formulas.

How many centimeters is a US men’s size 10?

For US men’s size 10, using the inverse of the formula:

inches=USmale+223=323=10.67 inches\text{inches} = \frac{\text{US}_{\text{male}} + 22}{3} = \frac{32}{3} = 10.67 \text{ inches} cm=10.67×2.54=27.1 cm\text{cm} = 10.67 \times 2.54 = 27.1 \text{ cm}

So, a US men’s size 10 corresponds to approximately 27.1 cm foot length.

How to convert UK size 9 to EU?

Using

EU=1.27×(9+23)+2=1.27×32+2=40.64+2=42.64\text{EU} = 1.27 \times (9 + 23) + 2 = 1.27 \times 32 + 2 = 40.64 + 2 = 42.64

Hence, UK 9 ≈ EU 43.

Why are women’s and men’s US sizes different?

Because the internal foot molds and design proportions differ. Typically, women’s shoes are narrower, with a one-size difference between men’s and women’s US scales.

Can I use the same size for running and casual shoes?

Not always. Running shoes usually require an extra 0.5 to 1 cm to accommodate foot expansion during movement. Always check specific manufacturer recommendations.

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