Luukaa runs in sizes 0-6. Here we like to think of 0 as an XS, 1 as a Small, 2 is in between small and medium, 3 a medium, 4 if you're between a medium and large, 5 a large, and 6 XL. This broad range of sizes means there is not a huge difference in the sizes. Usually people can go between two sizes comfortably.