What size is Nike US 9 in Adidas?

About Adidas US 9 (EU 42.5), matched by ~26.2 cm. Then adjust for the specific model.

Is a Nike 9 the same as a Adidas 9?

Not always. Labels can map to different foot lengths — use cm, then model fit.

Brand-to-brand size at a fixed US label — matched by foot length (cm), not guesswork.

Nike US 9 maps to about 26.2 cm on that brand’s chart. The nearest Adidas row at that length is US 9 / EU 42.5.

Same chart cm can still feel different on foot. Read the guides:

Nike: Air Force 1 '07 (runs big) · Dunk Low (true to size) · Pegasus 41 (true to size) · Vomero 5 (true to size) · Air Max 90 (true to size)

Adidas: Samba OG (runs narrow) · Gazelle (runs big) · Ultraboost 1.0 (true to size) · Campus 00s (true to size) · Handball Spezial (true to size)

What size is Nike US 9 in Adidas?: About Adidas US 9 (EU 42.5), via ~26.2 cm.
Where is the full size table?: Nike to Adidas compare.