ShoeSize Calculator

Form

Adult or Child

Adult Child

Foot Size

Results

Your ShoeSize

1 What is Shoe size?
2 How to Use This Calculator
3 Formula Used
4 Variables Explained
5 Worked Example
6 Why Use This Calculator?
7 Common Mistakes
8 Frequently Asked Questions
9 Sources & References
10 Related Calculators

What is Shoe size?

This shoe-size calculator turns a foot-length measurement into approximate adult US men’s, US women’s, UK and EU sizes, or child US, UK and EU sizes. It first converts feet, centimetres, metres or inches to inches and centimetres, then applies the page’s linear sizing formulas.

Shoe sizing is not universal. Brands use different lasts, toe allowances, widths and rounding, and child size ranges can cross system boundaries. Treat the numbers as a starting point for a brand chart and fitting, not a guarantee that a shoe will be comfortable or safe.

How to Use This Calculator

Choose adult or child; this selects a different formula set.
Measure foot length and enter a positive decimal value.
Select the measurement unit, not the desired shoe-size system.
Calculate and read the approximate regional sizes.
Compare the result with the manufacturer’s own chart and try the footwear when possible.

Measure both feet while standing, preferably near the time and with the socks intended for the shoe. Use the longer foot. The form asks for foot length, not the outside length of a current shoe.

Formula Used

After conversion to inches and centimetres, the page uses these approximations:

Adult US men = 3 × inches − 22
Adult US women = 3 × inches − 20.5
Adult UK = 3 × inches − 23
EU = 1.5 × centimetres
Child US = 3 × inches − 9.67
Child UK = 3 × inches − 10.67

Outputs are rounded to one decimal place. Retail sizes commonly use coarser increments.

Variables Explained

Input or output	Meaning
Age group	Selects the adult or child approximation.
Foot length	Heel-to-longest-toe measurement, not shoe outsole length.
Input unit	Feet, centimetres, metres or inches used for the measurement.
US men / women	Approximate adult US size scales with different offsets.
UK	Approximate UK size from the page’s inch-based equation.
EU	Approximation using 1.5 times entered foot length in centimetres.
Width and last	Fit factors the page does not calculate.

Worked Example

For an adult foot length of 10 inches, US men’s size is 3 × 10 − 22 = 8. US women’s is 30 − 20.5 = 9.5, and UK is 30 − 23 = 7.

Ten inches converts to 25.4 cm. The page’s EU approximation gives 25.4 × 1.5 = 38.1. A retailer may recommend a larger EU size because many charts include fitting allowance in their mapping.

The example demonstrates the exact page formulas. It does not establish equivalent fit across four actual shoes.

Why Use This Calculator?

Use the returned sizes to locate nearby entries on the manufacturer’s chart. When the answer lies between offered sizes, follow that brand’s guidance and consider shoe purpose, toe room, width and sock thickness. Hiking, running, work and formal shoes can fit differently.

Feet can differ in length and width, and swelling can change fit through the day. Children’s feet grow, so remeasure rather than relying on age or an old size. Do not add an arbitrary growth allowance unless supported by appropriate fitting guidance.

Mondopoint is a standardized system based on defined foot measurements, but the page returns regional approximations rather than a full Mondopoint width designation. For pain, deformity, diabetes-related foot risk or orthotic needs, seek advice from an appropriate footwear or healthcare professional.

Check fit while standing and walking. The heel should be secure, toes should not be compressed, and the widest part of the foot should align comfortably with the shoe. Materials may soften but a painful or numb fit should not be accepted on the assumption that length conversion is exact.

Common Mistakes

Measuring the shoe exterior instead of the foot.
Selecting centimetres for an inch measurement.
Using the shorter foot when the two differ.
Assuming the same printed size fits every brand and last.
Ignoring width, toe shape, socks and intended activity.
Treating a decimal output as a size every retailer sells.
Using an adult formula for a child or relying on age alone.

Frequently Asked Questions

Should I measure both feet?

Yes. Feet often differ, so use the longer measurement and check that width and shape also fit.

Is the result guaranteed to fit?

No. It is a formula-based starting point. Brand lasts, widths, materials and intended use change fit.

Why is the EU result a decimal?

The page applies a continuous formula and rounds to one decimal, while retailers usually offer selected whole or half-size steps.

Can I enter my current shoe size?

No. Enter measured foot length and its unit; the field does not accept a size label as input.

When is the best time to measure?

Measure under the conditions in which the footwear will be used, including suitable socks; feet may be larger later in the day.

Does the calculator include foot width?

No. Width and last shape are important fit dimensions that require a brand chart or fitting.

How often should a child be measured?

Remeasure regularly and whenever fit seems tight, rather than assuming an old size still applies.

Sources & References

MiniCalculators provides free tools for mathematics, finance, health, fitness, construction, statistics, conversions, and everyday questions. Each calculator includes a guide to its inputs, method, and limitations.