Does Nike run small?

What does "runs small" actually mean?

It is a claim about a brand's last, not about your foot. A last is the solid form a shoe is built around, and it sets the internal length, the width across the ball, the volume over the instep and the shape of the toe box. When people say a brand runs small, they mean that for a given size label the last gives less internal length or less width than the label led them to expect.

Two brands can both be accurate and still disagree, because the nominal scales are conversions of foot length and each brand decides how much room to add on top of foot length. That allowance is a design decision, made per last and often per model. It is the reason one person can wear one number in a running silhouette and a different number in a court silhouette from the same brand.

So the answerable question is never whether a whole brand runs small. It is how a specific model, in a specific width, compares with a shoe you already own and already know fits you.

Does ShirtMath have measured Nike shoe data?

No. The ShirtMath measurement set is garment measurements for tops, and it holds no measured Nike footwear. Nothing on this site should be read as a ShirtMath verdict on Nike sizing, and we would rather say that plainly than publish a number we did not measure.

The scanner cannot help here either. Photographing a shirt laid flat with a scale card is live; identifying or measuring a shoe from a photograph is not, and we do not claim it. If you arrived looking for shoe identification, see what shoes are these for the same boundary stated in full.

How do I check whether Nike runs small for me?

The reliable test uses a shoe you own, because a shoe that already fits is a physical control. Nothing below needs the brand to be honest with you, which is the point of it.

1. Measure your feet, both of them — stand on paper against a wall at the end of the day, mark the longest toe, and measure heel to mark. Feet swell through the day and one is usually longer. Size to the longer foot. The full method is in how to measure shoe size at home.
2. Write down what already fits — the brand, the exact model, the size and the width of a pair you are happy in. That pair is your reference, and a claim about Nike is only useful relative to it.
3. Read the brand's own chart for that model — Nike publishes a size chart and a fit note on its own product pages under its size and fit guide. A brand's own chart is the primary source for its own lasts, and it beats any aggregated table, including ours.
4. Check the width, not only the length — most reports of a brand running small are really reports of it running narrow. A wider foot in a standard width feels short because the foot sits further back on the last. Start with shoe width.
5. Buy where the return policy lets you be wrong — the honest answer for a shoe you have never worn is that you will find out on your feet. Order from a seller that lets you send it back, and try it on carpet at the end of the day.

Where does Nike publish its own conversion?

Nike states its own size conversions on nike.com, in the size and fit guide reached from a product page, and some models carry a fit note of their own on that page. Read the note for the model you want rather than a brand-level rule, because fit notes are written per silhouette. We do not reproduce another brand's chart here, and we do not paraphrase one into a number we cannot stand behind.

For a general cross-scale reference, our own tables are shoe size charts and international size conversion. Treat those as orientation. Where they disagree with the brand's own published chart for a specific model, the brand's chart wins.

Why do two shoes with the same number fit differently?

A size label is a name, not a measurement, and that is true across clothing as well as footwear. The same drift shows up in shirts, where a letter on a label can name genuinely different garments, which is why we measure garments rather than trust labels. That argument is set out in vanity sizing, and it transfers directly to shoes.

Four things move a shoe's fit independently of the number on the box: the last, the width fitting, the upper material and how much it gives, and the purpose of the model. A knit running upper relaxes with wear. A leather court upper relaxes less and later. Half sizes are a coarse grid laid over a continuous foot, so a foot can genuinely fall between two of them.

What can ShirtMath actually tell you today?

It compares garment measurements. Photograph a shirt laid flat with a scale card and the scanner returns its flat measurements, then matches those against published measurements across the catalogue. About half of scanner readings land within an inch of a tape measure, sleeve opening and bicep are the least reliable, and anything the scanner cannot read confidently is left blank rather than guessed.

That is the whole claim. No body scanning, no footwear, no fit prediction from a photograph of a shoe. Other questions of this shape are collected in answers.