This is based entirely on the type of hook you choose. Most hooks will specify what they are designed for. Individual hooks that are larger and made of metal like the Hogwarts House sets can hold heavier jackets and towels, whereas the Alohomora key hook is meant only for keys. The type of hardware you use for the installation process will also determine how much they can hold. If you use the standard hardware and the screws are only 1 inch long, physics will dictate how much weight and leverage can be placed on that one-inch screw when driven into your wall. If you are like my family and replace all standard hardware with three-inch screws, it can hold much more weight.