In general, when ordering, we recommend buying anywhere from a 1-6 month supply. Of course, everyone has their own preferences.
If you're trying to figure out how much your pets will eat, the truth is they are all different... some are bigger so they need more hay while others just have bigger appetites. Your rabbit should eat a compact pile the size of their bodies every day.
Guinea pigs may eat even more, and that's totally okay.
Here's a handy article about how much to feed, and how much the little ones should be eating: https://smallpetselect.com/uncategorized/feeding-unlimited-hay-vs-eating-unlimited-hay.
If you have a question, please contact Customer Service.