adidas generally runs about half a size smaller than Nike, and narrower through the midfoot. If you take EU 42 in Nike, start at EU 42.5 in adidas.
That is the rule. It holds often enough to be useful and breaks often enough to be worth understanding.
Where the difference comes from
Each brand builds shoes on its own last, the foot-shaped mould a shoe is made around. Nike's lasts tend to run longer and higher through the toe box. adidas lasts tend to be shorter and flatter, particularly on the court silhouettes.
Neither is wrong. They are just different shapes, sold under the same numbers.
Model by model
- Stan Smith and court styles — snug and narrow. Half a size up from your Nike size, and a full size up if you have wide feet. More on the shoe in the Stan Smith, explained.
- VL Court and Grand Court — closer to true to size than the Stan Smith, but still narrower than a Nike equivalent.
- Air Force 1 — the outlier in the other direction. It runs long, so it is more like a full size apart from a Stan Smith. See does the Air Force 1 run big.
- Running shoes, both brands — closest to true to size, because a running last is built around the actual foot rather than a look.
Width is the part people miss
Most sizing regret is not about length. It is about width, and going up a size to fix a narrow shoe gives you a shoe that is too long and still narrow. If a model is known to run narrow, that is worth knowing before you order rather than after.
Where we know a pair runs narrow or short, the fit note on the listing says so.
The number that settles it
Both brands print their sizes against a real foot length, so a measurement in centimetres cuts through the whole argument. Our size conversion chart has the EU, UK, US and centimetre columns side by side, and the 30-second measuring method gets you the number.
If it still lands wrong, there are 7 days to send it back for a full refund — see the refund policy. We do not swap sizes, because each pair here is one of one; the FAQ explains why.