Measuring child’s feet for new shoes - do I add a cm?

[Onedropbeat]

I need to buy dc new shoes.

I’ve measured the length (162mm) which means I can use the size guides on the shoe website.
But am I also meant to add some to get the right size? He’s 3, so some growing room maybe?

And if so how much do I add?

I bought DS2 some shoes recently, his fooy was exactly 11cm and I bought size 3 (11cm) and they fit perfectly.

They are very soft baby shoes though which might make a difference to fit.

*foot