Confused about Puma King 20 Sizing

Everything I’ve read says they run short and to order half a size up, and I usually wear a 10.5 in Mercurials so I’d be looking at an 11 right?

Well when I look at the cm on the box, the Pumas say the cm for a US size 11 is 29 - which is like a 12.5 (Nike 10.5 is like 27 cm).

Does anyone have any experience with this? Looking to get from an independent buyer not retail so I’d have to make sure this size is correct before I buy