What Is This Shoe Size Conversion Calculator
This adult shoe size converter looks up one entered label or heel-to-toe measurement in a selected published manufacturer chart. It returns the corresponding US men's, US women's, UK, EU, centimetre, inch, and Mondopoint references from the same discrete row rather than manufacturing a smooth answer from a universal equation.
Choose either the Adidas or Nike adult reference because their labels do not align at every foot length. The result also shows nearby rows and an alternate-chart illustration, making disagreement visible instead of hiding it behind one supposedly exact conversion.
How to Use the Shoe Size Conversion Calculator
- Choose the Adidas or Nike published adult reference chart. Use the chart for the exact product when it is available instead of assuming either reference applies to every shoe.
- Select the input system you actually have: US men, US women, UK, EU, measured foot length in centimetres or inches, or Mondopoint millimetres.
- Enter the printed adult size or a standing heel-to-toe measurement. Do not enter shoe interior length as though it were foot length.
- Choose nearest listed row or next listed row for a value that falls between chart entries. Exact chart labels remain exact regardless of this setting.
- Select Match chart row, then read the match status, all converted labels, listed foot length, nearby-row table, and fit limitations together.
- Before buying, compare the result with the exact model's current size chart, width choices, fit notes, socks, intended activity, and return policy.
How to Measure Foot Length for Shoe Size
Measure on a hard, flat surface while standing with weight distributed normally. Mark the back of the heel and the tip of the longest toe with the pencil held upright, then measure the straight distance between those points. Repeat for the other foot and use the larger relevant measurement when consulting a length chart.
Timing and technique matter. Adidas advises measuring at the end of the day, while Nike instructs users to measure both feet and use the longer measurement. A traced outline, angled pencil, compressed toes, thick border line, or seated measurement can shift the result enough to cross a chart row.
- Measure both feet while standing.
- Use the longest toe, which is not always the big toe.
- Record the value before rounding.
- Keep centimetres and inches explicitly labeled.
- Re-measure rather than relying on an old remembered size.
Why Shoe Size Conversion Uses Charts, Not One Formula
Shoe size systems developed differently, and manufacturers interpret labels through their own lasts, grading, and product decisions. ISO 19407:2023 describes conversion tables as consumer guidance based on foot length and notes that historical development has prevented a single complete solution to shoe-size conversion.
For that reason, this calculator chooses an actual listed row. It does not use shortcuts such as adding a fixed number to every EU size or assuming the men's-to-women's difference is identical for all brands. Values between rows are labeled as nearest or next listed rather than displayed as fictional quarter sizes.
How to Read US, UK, EU, and Mondopoint Results
US men's, US women's, and UK labels typically progress in half-size steps, while an EU chart may use whole, half, or one-third steps. Mondopoint identifies footwear through foot measurements in millimetres under ISO 9407. A displayed 263 mm reference therefore communicates a length basis more directly than a bare regional label, but it still does not determine the complete shape of the shoe.
Centimetre or JP labels printed on a box are not always identical to measured foot length. Nike explicitly distinguishes its CM box label from Foot Length (cm). This page labels the measurement as heel-to-toe length and derives Mondopoint context from that length; it does not silently treat every printed CM label as the same quantity.
Men's and Women's US Shoe Size Conversion
A common men's-to-women's shortcut can be useful inside one brand chart but is not a universal gender conversion. The Adidas reference used here lists US women's one size above the corresponding US men's label across its shared adult rows. The Nike reference lists the women's label 1.5 sizes above the men's label in its published chart.
Those labels do not describe width, volume, heel shape, or a person's gender. Someone shopping across departments should compare measured length and product-specific width information rather than relying only on the numerical difference.
Worked Shoe Size Conversion Examples
These examples demonstrate chart lookup rather than a universal conversion formula. Each answer is valid only as a reference to the named chart and should be checked against the intended product.
| Input | Reference | Matched labels | Interpretation |
|---|---|---|---|
| US men's 9 | Adidas adult | US women's 10 / UK 8.5 / EU 42 2/3 | Listed heel-to-toe length is 26.3 cm |
| US men's 9 | Nike adult | US women's 10.5 / UK 8 / EU 42.5 | Same US label, different cross-system row |
| 26.3 cm | Adidas adult | US men's 9 / EU 42 2/3 | Exact listed length |
| 26.4 cm | Adidas adult | Nearest: US men's 9 / Next: 9.5 | Between-size rule changes the selected row |
| 263 mm | Adidas adult | US men's 9 / UK 8.5 | Mondopoint input is interpreted as millimetres |
What the Shoe Size Result Workspace Includes
- Two separately identified adult manufacturer reference charts.
- US men's, US women's, UK, EU, centimetre, inch, and Mondopoint inputs.
- Exact, nearest, or next-listed match status.
- All cross-system labels from one selected chart row.
- Lower and upper boundaries surrounding the entered value.
- A five-row neighborhood around the selected size.
- An alternate-chart illustration at the nearest listed length.
- A visible warning that width and arch fit are not inferred.
Benefits of a Chart-Aware Shoe Size Converter
A chart-aware converter preserves the source of the answer. That is more useful for online shopping than a formula-only result because a user can see whether the input matched a published row, fell between entries, or produced a different label in another brand reference.
Nearby rows also make the size step visible before checkout. The workspace helps prepare a shortlist, compare labels on an existing pair, and communicate a measured length, while leaving the final fit decision to the actual shoe and seller information.
Common Shoe Size Conversion Use Cases
Use the calculator when comparing a US listing with an EU or UK label, shopping across men's and women's departments, checking an imported product, interpreting a Mondopoint marking, or estimating a starting size from a newly measured adult foot.
It is also useful for spotting when two websites use different charts. Save the original label, selected chart, and measured length beside the conversion so another person can reproduce the lookup.
Length Alone Cannot Determine Width, Arch, or Last Fit
Brannock fitting guidance treats heel-to-toe length, heel-to-ball or arch length, and width as separate measurements. It advises using the larger of heel-to-toe and arch-length sizing and fitting the larger foot. A length-only web converter does not have those measurements and must not imply that it does.
Manufacturer width words and letters are not fully standardized, and shoes built on different lasts can feel different at the same printed size. Toe box shape, instep volume, heel hold, intended activity, orthotics, socks, swelling, and materials can all affect fit.
Adult and Children's Shoe Sizes Must Stay Separate
This calculator is intentionally adult-only. Children's systems use age and growth considerations, different label ranges, and dedicated charts. A youth label that resembles an adult number should not be passed through the adult table by assumption.
Use the current children's chart from the manufacturer or a trained fitting service. Re-measure growing feet regularly and check both length and width rather than adding an unsupported growth allowance to an adult conversion.
Accuracy, Fit, and Trust Notes
For an exact label in the selected stored chart, the lookup returns the corresponding row without interpolation. A between-row input follows the chosen rule and is marked accordingly. The alternate chart is only an illustration of brand variation; it is not a recommendation to buy that alternate label.
The stored chart was reviewed against official Adidas and Nike pages on August 11, 2026. Published charts can change. This independent site is not affiliated with or endorsed by either company, and trademarks belong to their respective owners. Always recheck the current product page before a purchase with meaningful cost or limited returns.
Official Shoe Sizing and Measurement References
These primary sources explain the conversion-guidance boundary, Mondopoint, manufacturer chart rows, and professional fitting measurements. The links support the method but do not certify that a particular shoe will fit.