How about the same number as your Jackets or shoes? Why do I say this? Well, with Jackets or shoes, there are colors, occasions, styles and function - same in hats. The number of hats would be proportional to your wardrobe in Jackets or shoes surely? It would be no use to have 20 shoes, but 3 hats....or is this a hat site and it should be the other way round!!??