Depends on the size of your rabbit, what other foods you feed, and the amount that goes to waste. A 50 lb bale lasts me a month. That's for 10 rabbits that weight 35 lbs altogether, so about 1.5 lbs of hay, per pound of rabbit., per month That includes a bit of hay peed on, not eaten, and wasted. I also feed a small amount of pellets and veggies. Generally you can plan on feeding around 1-2 lbs of hay, per lb of rabbit, per month. That's just approximate and will vary with each rabbit.