What size is UGG US 8 in Crocs?

About Crocs US 7.5 (EU 40.5), matched by ~25.2 cm. Then adjust for the specific model.

Is a UGG 8 the same as a Crocs 8?

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.

UGG US 8 maps to about 25.2 cm on that brand’s chart. The nearest Crocs row at that length is US 7.5 / EU 40.5.

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

UGG: Classic Mini (true to size) · Classic Short II (true to size) · Tasman Slipper (true to size) · Classic Ultra Mini (true to size)

Crocs: Classic Clog (runs wide) · Echo Clog (true to size)

What size is UGG US 8 in Crocs?: About Crocs US 7.5 (EU 40.5), via ~25.2 cm.
Where is the full size table?: UGG to Crocs compare.