What size is Adidas US 9 in Reebok?

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

Is a Adidas 9 the same as a Reebok 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.

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

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

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

Reebok: Club C 85 (true to size)

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