I just found this awesome online tool for working out your size for lots of UK high street stores: What Size Am I?
Online shops need to start providing tools like this. Though I think they need to eventually offer this per item of clothing – with sleeve and pant length, plus shoulder width.
These days I have three ways of shopping:
1) I try something on at the shops, then come home, and try and find it cheaper online (not always possible in Australia where many stores charge for postage).
2) I see something I like online, and then I look for a bricks and mortar store to try it on.
3) Very rarely, I will just buy something online (without trying it on) – this is mostly shoes, shirts, jewellry, handbags, scarves, tanks and jeans.