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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A shoe size label is a shorthand for a measurement system, not a universal measurement. A foot that measures 26.0 cm may appear as US men's 8.5, UK 7.5, EU 41.5, JP 26, CN 260 mm, or KR 260 mm depending on the chart. Those labels look inconsistent because regional systems use different starting points, units, and rounding habits.

The most reliable anchor is heel-to-toe foot length. It can be measured directly and translated into the sizing systems printed on shoe boxes, product pages, and retailer charts. The difficulty is that some labels stay close to foot length, while others are based on last length, the internal shoe length after adding room for toes and movement. A size conversion therefore needs both the body measurement and an allowance assumption.

How common shoe sizing systems relate to foot length and last length
System family	Main basis	What commonly goes wrong
JP, MX, CN, KR	Foot length, shown in centimeters or millimeters.	Centimeter and millimeter values are easy to mix up, especially around 26 cm and 260 mm.
US and UK	Last length in inches, expressed as nominal retail sizes.	Changing toe room can move the result by a half size or more.
EU	Last length in centimeters using Paris-point style increments.	Half EU values help comparison, but many brands sell only whole EU labels.
BR	An EU-derived estimate with an offset.	Brazil labels vary enough that retailer charts should decide the final choice.

Length is still only one part of fit. Width, instep height, toe-box shape, arch support, socks, material stretch, and swelling over the day can change the size that feels right. A conversion is strongest when it catches unit mistakes, translates between regional labels, or gives a first comparison before reading a brand chart. It is weaker when treated as proof that a particular model will fit.

One common mistake is to translate a printed label without checking the unit behind it. JP and MX use centimeter-style labels, while CN and KR use millimeter labels. Entering 260 as centimeters instead of millimeters creates an impossible adult foot length; entering 26 as millimeters creates an infant-sized result. The number itself is not enough without the selected system.

For shopping, measure both feet, use the longer foot, compare the translated labels with the seller's chart, and treat disagreement as a warning. Children's shoes, orthotics, high-performance footwear, and medical foot conditions need extra caution because growth room, support, and pressure points can matter more than the nearest length label.

How to Use This Tool:

Start from the value you trust most, then use the matrix, warnings, and charts to check whether the converted labels still fit the real shopping context.

Choose Input type. Use Foot length (cm) or Foot length (in) for a fresh measurement, or choose the regional label printed on the shoe tag when you are translating an existing size.
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 mode such as foot length, JP, or MX.
If the warning says the foot length is outside the typical adult range, first check whether the selected input type matches the number you entered.
Set US headline scale when the starting input is foot length. This chooses whether the summary promotes US men or US women; the size matrix still includes both US rows.
Pick a Fit allowance. The presets fill common values: 0.5 cm for snug, 1.5 cm for standard, and 2.0 cm for roomy. This allowance changes US, UK, EU, and BR because those systems 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.
Rounding can make the effective toe room differ from the allowance you typed, especially with whole-size steps or a floor setting.
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 change the BR offset.
Review Size Matrix, Toe Room Gauge, and Warnings. Use downloads or JSON only after the foot length, allowance, and primary label agree with the retailer chart you plan to use.

Interpreting Results:

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

Foot length (cm) is the shared measurement anchor. If it does not match the measurement you trust, the input type is probably wrong. Last length (cm) is foot length plus the selected allowance, so it explains why roomier settings can raise US, UK, EU, and BR labels while JP, MX, CN, and KR stay tied to the measured foot.

How to read shoe size converter result areas
Result area	What it shows	Useful check
Size Matrix	Foot length, allowance, last length, US, UK, EU, BR, JP, MX, CN, KR, and a cleaned width note when valid.	Compare the matrix with the seller's chart instead of using one label alone.
System Crosswalk	A chart that places nominal size labels and foot-length systems side by side.	Use it for orientation; the axes mix size numbers and measurement-based labels.
Toe Room Gauge	The effective toe room implied by the rounded primary size.	Check whether rounding made the shoe tighter or roomier than the allowance suggests.
Sizing Step Chart	The selected retail increments converted to millimeters.	Spot coarse whole-size jumps before treating a result as precise.
Warnings	Adult range, unusual allowance, EU half-size availability, and BR approximation notices.	Resolve warnings before using the result for buying or recordkeeping.

A width code such as D, B, 2E, Wide, or Narrow is kept as a note after spaces are removed and letters are uppercased. It documents a fit preference, but it does not change the length formulas.

Technical Details:

Shoe size conversion starts by reducing every supported input to foot length in centimeters. Direct foot-length inputs use the entered measurement, inch inputs multiply by 2.54, JP and MX use centimeter labels directly, and CN and KR divide millimeter labels by 10. Labels based on last length are reversed by undoing their size formula and subtracting the selected allowance.

After foot length is known, the conversion adds fit allowance to get last length for US, UK, EU, and BR calculations. JP, MX, CN, and KR remain tied to foot length. The result is then rounded to the selected retail step using nearest, floor, or ceil. That rounding step is why the displayed label can imply a little less or more toe room than the allowance field itself.

Formula Core:

The shared variables are foot length Lfoot in centimeters, allowance A in centimeters, last length Llast, BR offset O, retail step q, and rounding mode Rmode.

\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}

JP and MX display foot length in centimeters. CN and KR display the same foot length in millimeters. US and UK use three size points per inch of last length, EU uses 1.5 size points per centimeter of last length, and BR is derived from the EU-style result with the selected offset.

Input labels converted back to foot length
Input family	Back-solving rule	Caution
Foot length, JP, MX	Use the centimeter value directly, or convert inches to centimeters.	The value should look like a foot measurement, not a nominal regional size.
CN, KR	Divide the millimeter label by 10 to get centimeters.	A missing or extra 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 EU labels may be useful mathematically even when the retailer sells whole sizes only.
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 an EU-equivalent label, then reverse the EU rule.	The Brazil result is approximate and should be checked against the seller's Brazil chart.

Shoe size warning and toe room rules
Signal	Rule	What to check
Adult range warning	Foot length below 18 cm or above 31 cm.	Confirm the input type and units before trusting any regional label.
Allowance warning	Allowance below 0.5 cm or above 2.0 cm.	Decide whether the fit is intentionally snug, roomy, or outside normal retail assumptions.
Toe room status	Under 8 mm tight, 8 to 15 mm comfortable, above 15 mm roomy.	Compare the gauge with the intended shoe type and brand fitting notes.
Width note	Letters and digits are kept after spaces are removed.	Use it as documentation only; width does not alter the length conversion.

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 nearest rounding to the default half-size step, the displayed result is US M 8.5.

Accuracy Notes:

The conversion is length-based. It does not model foot volume, toe-box shape, arch support, upper stretch, sock thickness, swelling, or how a brand grades a particular product line. Treat the result as a chart comparison and sanity check, not as a guarantee of comfort.

BR is marked approximate because it is derived from EU sizing plus the selected offset.
EU half sizes can appear in the calculation even when a retailer sells whole EU labels only.
Children's shoes, orthotics, performance footwear, and medical needs may require more careful fitting 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, the recommendation is US M 8.5, last length is 27.50 cm, 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 resolves to about 26.50 cm. Compare that back-solved length with your measured foot before trusting the translated rows.

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 the warnings flag the unusual allowance and the toe room gauge moves into the tight range.

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 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, comparing a retailer chart, or checking what a known size means in another region.

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 adding or removing 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 size recommendation?

No. The width code is kept as a note in the results and exports. It documents a fit preference, but it does not change foot length, last length, or any regional formula.

Why does the BR result need extra caution?

The BR row is derived from an EU-style 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 internal 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, often 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.