The smallest cup I found was a B and I bought it although I am really closer to an A cup. Even though it is a little bit big I love it and would order more. It gives me a nice natural-looking shape and it is extremely comfortable. I actually emptied out my drawer and threw out my old bras because I can't see myself going back to them. The straps (finally) stay on all day and I don't need to keep sticking my hand in my shirt to put back the strap. Will definitely order more.