Leggings should feel like a second-skin on your body. It should round you up across the butt, thighs, and legs, and should not be too tight so that you feel restricted when you are moving, or too loose so that you always have to keep pulling them up.
The right size will not allow your underwear or skin to become visible when you do a squat or stretch out during workout
Different types of leggings have different tolerance in sizing. Generally speaking, seamless leggings, which are knitted, are more stretchy. A person with a size M could feel good with a size S too. Standard leggings are more up to your standard size and less stretchy as seamless leggings. Leather leggings are generally tight and you need to be careful when choosing a size.
