The short answer (pardon the pun) is that if you are 5ft 3ins or under (160cm or less), according to the UK fashion industry you are petite. Being petite is defined by your height rather than by your weight or dress size.
If you’re reading this and you’re 5ft 4” or 5ft 5” and find that most sleeves are too long and that you have to shorten your trousers all the time, try the petite stores and “petite friendly” stores for size. Petite stockists can be found on the petite stores page.
If you are reading this blog post, I presume that you are petite. I’d be interested in knowing: