Shoe Size Converter

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Input type:

Choose foot length for best accuracy, or pick the region printed on the shoe tag.

Size or foot length:

Enter one number in the selected unit, for example 26, 9.5, 43, or 260.

US headline scale:

Use the scale you will shop first; it does not hide the other US conversion.

Fit allowance:

Enter cm of extra room; the preset menu can fill common allowances.

Rounding:

Nearest is balanced; Floor checks tighter labels, Ceil checks roomier labels.

Width code:

Examples: B, D, E, 2E, Wide, or Narrow.

US/UK step:

Use 0.5 for half sizes; use 1 when a brand lists whole sizes only.

EU step:

Use 0.5 for half EU labels, or 1 for whole EU sizes.

JP/MX step (cm):

Use 0.5 cm for common retail steps; smaller values can overstate precision.

CN step (mm):

Use 5 mm for common CN labels; enter 1 only for a brand-specific chart.

KR step (mm):

Use 5 mm for common KR labels; enter 1 only for a brand-specific chart.

BR step:

Use 1 for whole BR labels; use 0.5 only if the brand lists half sizes.

BR offset:

Set -2 for the common EU minus two shortcut, or 0 to keep the raw estimate.

Field	Value	Copy
{{ r.label }}	{{ r.value }}

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Buying shoes across regions turns a simple body measurement into several different labels. A person who wears a US men's 8.5 might see an EU 41.5, a UK 7.5, a JP 26, a CN 260 mm, or a KR 260 mm on nearby charts. Those numbers look unrelated because each sizing system grew from its own measuring habit, unit, and retail convention.

Foot length is the most useful anchor because it can be measured directly. The tricky part is that not every size label describes the same physical thing. Some systems stay close to the bare foot measurement, while others are based on the shoe last, the shaped form that leaves extra internal length for toe room. The same foot can therefore produce two families of results: foot-length labels and last-length labels.

Length also does not settle fit by itself. Width, instep height, upper material, socks, foot swelling, and the brand's own last can all change the size that feels right. A conversion is strongest when it helps compare charts or catch a unit mistake. It is weaker when it is treated as a guarantee that a specific shoe will fit.

Common factors that affect shoe size conversion
Factor	Why it changes the label
Measured foot length	The heel-to-toe number is the common reference point for size conversion.
Fit allowance	Extra room turns foot length into last length for systems that model the inside of the shoe.
Retail step	Half sizes, whole sizes, and 5 mm steps round the same raw size differently.
Brand chart	Manufacturers can tune their lasts and recommendations around style, material, and intended fit.

One common mistake is to compare labels without checking the unit underneath. JP and MX labels are expressed in centimeters, CN and KR values are expressed in millimeters, and EU, UK, US, and BR labels are nominal retail sizes. Entering 260 as centimeters instead of millimeters turns a normal adult foot into an impossible measurement.

The most reliable shopping pattern is to measure the foot, compare the converted labels with the seller's chart, and treat a disagreement as a reason to pause. Children's shoes, orthotics, performance footwear, and medical foot conditions need more caution because growth room, support, and pressure points matter as much as the length label.

How to Use This Tool:

Start with the input that carries the least uncertainty, then use the warnings and charts to check whether the result still makes sense.

Choose Input type. Use Foot length (cm) or Foot length (in) for a fresh measurement. Use US Men, US Women, UK, EU, JP / Mondopoint (cm), MX (cm), CN (mm), KR (mm), or BR when translating a printed label.
Enter Size or foot length and check the unit suffix. A value such as 260 belongs in a millimeter mode such as CN or KR, while 26 belongs in a centimeter foot-length mode.
Set US headline scale when the starting point is foot length. It chooses whether the summary promotes the US men or US women label; the size matrix still shows both rows.
Pick a Fit allowance. The presets set 0.5 cm for snug, 1.5 cm for standard, and 2.0 cm for roomy. This allowance affects US, UK, EU, and BR because those rows are derived from last length.
Choose Rounding. Nearest selects the closest retail step, Floor checks the tighter available step, and Ceil checks the roomier available step.
Open Advanced only when a brand chart uses unusual increments. You can adjust US/UK, EU, JP/MX, CN, KR, and BR step sizes, add a width note, or shift the approximate BR mapping with BR offset.
Review Warnings before using the recommendation. Fix the mode or value if the foot length is outside a typical adult range, if the allowance is unusual, or if a BR or half-EU result needs a retailer chart check.

Interpreting Results:

Recommended Size is the headline label for the current input path. If the input is a regional label, the headline remains in that region. If the input is foot length, the selected US headline scale controls whether US men or US women appears first.

Foot length (cm) is the shared anchor. If it does not match the measurement you trust, the input mode is probably wrong. Last length (cm) is foot length plus the selected allowance, so it explains why roomy settings push US, UK, EU, and BR labels upward.

Size Matrix lists foot length, allowance, last length, US, UK, EU, BR, JP, MX, CN, KR, and the cleaned width note when one is valid.
System Crosswalk compares nominal labels with foot-length systems. It is useful for orientation, but the bars mix retail size numbers and centimeter-based labels.
Toe Room Gauge reports effective toe room from the rounded primary size. It can differ from the allowance you typed when rounding moves the label up or down.
Sizing Step Chart converts the selected retail increments into millimeters, which makes coarse whole-size jumps easier to see.
JSON, CSV, DOCX, and chart downloads help save the conversion when you need to compare it with a retailer chart later.

Technical Details:

Shoe size conversion is a deterministic mapping from a starting label or measurement into foot length, then into other regional labels. International footwear sizing guidance treats foot length as the logical reference because it can be measured across systems. Mondopoint-style sizes follow defined foot measurements, while traditional US, UK, and EU labels are nominal systems that need a last-length assumption.

The important technical split is foot length versus last length. Foot-length systems keep the value close to the measured foot. Last-length systems add fit allowance before conversion, then round to the selected retail step. Rounding can change the effective toe room because a displayed half size or whole size implies a slightly different last length than the unrounded calculation.

Formula Core:

The shared measurement is foot length in centimeters. Last length adds the selected fit allowance before last-based systems are calculated.

\begin{array}{lcl} L_{last} & = & L_{foot} + A \\ S_{UK} & = & 3 \frac{L_{last}}{2.54} - 25 \\ S_{US men} & = & 3 \frac{L_{last}}{2.54} - 24 \\ S_{US women} & = & 3 \frac{L_{last}}{2.54} - 23 \\ S_{EU} & = & 1.5 L_{last} \\ S_{BR} & = & S_{EU} - 2 + O \\ S_{CN}, S_{KR} & = & 10 L_{foot} \\ S_{display} & = & R_{mode} (\frac{S_{raw}}{q}) q \end{array}

Here Lfoot is foot length in centimeters, A is allowance in centimeters, Llast is last length, O is the BR offset, q is the selected retail step, and Rmode is nearest, floor, or ceil rounding. JP and MX use foot length in centimeters, while CN and KR show the same foot length in millimeters.

How input labels are converted back to foot length
Input family	Back-solving rule	Key caution
Foot length, JP, MX	Use the entered centimeter value directly, or convert inches to centimeters when needed.	The number should look like a normal adult foot length, not a regional size label.
CN, KR	Divide the millimeter label by 10 to get centimeters.	A missing zero changes the result by a full order of magnitude.
EU	Divide the EU label by 1.5 to estimate last length, then subtract allowance.	Half-size availability varies, so rounded EU results may not exist for every brand.
UK, US Men, US Women	Reverse the three-sizes-per-inch formula, convert inches to centimeters, then subtract allowance.	Changing allowance changes the inferred foot length when starting from a printed label.
BR	Add 2 and subtract the BR offset to estimate the EU-equivalent label, then reverse the EU rule.	The Brazil row is approximate and should be checked against a retailer chart.

Shoe size conversion basis by supported system
System	Basis used	Default step	Main caution
US Men, US Women, UK	Last length in inches	0.5 size	Allowance and rounding can move the displayed label by a half size or more.
EU	Last length in centimeters	0.5 size	Half EU labels are useful for comparison, but many retailers list only whole EU sizes.
JP and MX	Foot length in centimeters	0.5 cm	Fit allowance does not change these labels because they follow foot length.
CN and KR	Foot length in millimeters	5 mm	Millimeter labels are the fastest place to catch a cm/mm input mix-up.
BR	EU-derived estimate with offset	1 size	Brand charts can differ by about one size from the generic mapping.

Warnings and toe room status rules
Signal	Rule	What to check
Adult range warning	Foot length below 18 cm or above 31 cm	Confirm that the selected input mode matches the number you entered.
Allowance warning	Allowance below 0.5 cm or above 2.0 cm	Decide whether the fit is intentionally very tight or very roomy.
Toe room status	Under 8 mm tight, 8 to 15 mm comfortable, above 15 mm roomy	Use the gauge as a quick check, then compare with the brand's fitting notes.
Width note	Letters and digits are kept after spaces are removed	Width is documented in results, but it does not change length formulas.

For example, a 26.0 cm foot with 1.5 cm allowance gives a 27.5 cm last. The US men's raw value is 3 x (27.5 / 2.54) - 24, or about 8.48. With the default half-size nearest setting, the displayed result is US M 8.5.

Accuracy Notes:

The conversion is length-based. It does not model width volume, toe-box shape, arch support, upper stretch, or the way a specific brand grades sizes across a product line. Treat a conversion as a chart comparison, not a replacement for the seller's fit guidance.

A width code such as D, B, or 2E is recorded only when it contains letters and digits after spaces are removed. It does not change the size math.
BR is marked approximate because the result is derived from EU sizing plus the selected offset.
Children's sizing, orthotics, performance footwear, and medical needs can require more fit room or closer professional guidance than an adult length conversion provides.

Worked Examples:

Measured everyday fit. Enter 26.0 with Foot length (cm), keep Fit allowance at 1.5 cm, and leave Rounding on nearest. With the US headline scale set to men, Recommended Size shows US M 8.5, Last length (cm) shows 27.50, and the matrix includes UK 7.5, EU 41.5, JP 26, MX 26, CN 260 mm, and KR 260 mm.

Known EU label back to foot length. Choose EU, enter 42, and keep the standard 1.5 cm allowance. The headline remains EU 42, while Foot length (cm) resolves to about 26.50. Compare that back-solved foot length with your own measurement before trusting the translated labels.

Too-tight settings. With the same 26.0 cm foot, set allowance to 0.4 cm and choose floor rounding. The result still calculates, but Warnings flags the unusual allowance and the toe room gauge moves toward tight. That is a stop-and-check result, not a comfortable default.

Unit mistake. If 260 is entered as Foot length (cm), the adult range warning appears because the measurement is impossible. Switching the input type to CN (mm) reinterprets the same number as 26.0 cm and returns the size matrix to a normal range.

FAQ:

Should I start from foot length or from a shoe label?

Start from measured foot length when you can. Use a shoe label when you are translating an existing tag or a retailer chart into another regional system.

Why does allowance change US, UK, and EU sizes but not CN or KR?

CN and KR follow foot length in millimeters. US, UK, EU, and BR are based on last length, so changing the allowance changes those labels.

Why is toe room different from the allowance I entered?

Toe room is calculated from the rounded primary size. If rounding moves the displayed label up or down, the implied last length and effective toe room move too.

Does the width code affect the recommendation?

No. The width code is a note in the summary and exports. It helps document a shopping preference, but it does not change foot length, last length, or any size formula.

Why does the BR result need extra caution?

The BR row is derived from an EU estimate and the selected BR offset. Brand charts can differ by about one size, so compare that row with the seller's Brazil chart before buying.

Glossary:

Foot length: The heel-to-toe measurement used as the shared anchor for conversion.
Last length: The shoe-length estimate after fit allowance is added to foot length.
Fit allowance: Extra length added for toe room before last-based systems are rounded.
Mondopoint: A footwear sizing approach based on defined foot measurements, commonly expressed in millimeters or centimeters.
Retail step: The increment a size label can use, such as half sizes, whole EU sizes, or 5 mm CN and KR labels.

References:

ISO 19407:2023 Footwear - Sizing - Conversion of sizing systems, International Organization for Standardization.
ISO 9407:2019 Footwear sizing - Mondopoint system of sizing and marking, International Organization for Standardization.