When it comes to bean bags, size definitely matters. If you're looking for a bean bag that's big enough for an adult, you'll want to choose one that's at least 36 inches in diameter. However, if you plan on using your bean bag for lounging or sleeping, you may want to opt for a larger size. Bean bags that are 48 inches or more in diameter offer plenty of room for stretching out, and they're also great for cuddling up with a friend or loved one. No matter what size you choose, make sure to pick a bean bag that's comfortable and supportive.