When fitting full foot fins they should be snug, but not too thigh nor too loose, and should be sized according to your shoe size.
Many manufactures may size fins across a few sizes (For example, 8-9, 10-12), in this case your toes might stick out from the front of the foot pocket, this is perfectly fine unless it feels uncomfortable. If it does, then you should get the next size down.
Open- heel fins are not generally size by shoe size, but by bands (for instance, M, L, XL). Use the size chart below to choose the right shoe size for you.
A general rule of thumb when buying your adjustable open heal fins is to add one size up to leave room for your booties. When trying them on for fit be sure to do so with your booties on. (Learn how to choose the best dive boots)
Scuba Fins Size Chart
|Men's Shoe Size||3 - 4||5-6||7-8||9-11||12-13|
|Women's Shoe Size||5-6||7-8||9-10||11-12||-|