I always say this to people about coats, my favourite coat is a 24 and I'm an 18/20. I only got it because I loved it and it looks really good over sized with the elastic belt on it and I can wear millions of layers under without struggling to breatheHer coat won't even do up!!! Mind you every time she has bought a coat, and that seems a lot of times, they always look too tight. Bav it's always better to go up a size in a coat so you can get clothes underneath and then you don't end up looking like a stuffed sausage!!