I mostly shop online. It is very difficult to find if the trousers/pants are actually true to size or vanity sized. I typically find that there is a 5 cm difference between the two... i.e. a size 32 has an actual 34" waist. 5 cm.
I don't have actual measurements but I ordered and received a medium lambs wool v-neck but returned it because I thought it was too baggy. I have a ~39" chest, 34" waist. I have long arms so didn't try to exchange for a small.