What size waterproof bag should I get?

The most common size for smaller dry bag is 2---5L. 2L dry bag is ideal for keys, cell phones. The 5L dry bag can allow a towel to put in. The medium size is 10---20L that is great for few cloth, while the 30 to 40L are performed as larger size that is great for camping, boating. Well, there are some extra large sizes of dry bags such as 50-80L that are for diving as they are great keep your wetsuits.