The answer is yes; compostable cups come in different sizes. The most common sizes are 12 oz and 16 oz. However, there are also 20 oz cups available for larger beverages. You can find these at most coffee shops and restaurants that use compostable cups. The other thing you should know is that some of the smaller sizes of compostable cups have lids that can be reused. For example, if you buy an iced coffee from Starbucks, they will give you a lid to use with their paper cups. The lid has a tab on the side that allows you to tear it off so you can throw it away separately from the cup itself.