This top fits more snugly than I expected. I'm a size 10 - 12 and I bought a L as I'm between M and L in MP sizes. If you prefer tops to have a little more room in, you might need to size up. It's also quite short, it does cover the top of my shorts/leggings but I hope it doesn't ride up and show my midriff as it's such a snug fit. Time will tell... The fabric is also quite thick so it will be good for doing Bootcamp outdoors in the winter but maybe not so good in the summer.