The current metro area population of Cardiff in 2023 is 488,000, a 0.62% increase from 2022.
Barry , Penarth ,is within this figure.
I’d argue it’s bigger again than Newcastle and Gateshead if you include Caerphilly some of the towns bordering Cardiff in RCT and the like.
Cardiff Council population for 2023 is getting very close to 400k. The urban population is around 1.3m