We have 7 chickens and a 50 lb bag has been lasting about 5 weeks. They free range only 2-3 hours a day, about 5 days a week, but get scraps/treats nearly every day. Now that it's colder I've been giving some scratch too. I haven't seen how long the feed lasts this time of year, I figure the colder, shorter days and the scratch might change things up a bit.