I bought a 10lb bag (I think, may have been more) about a year ago. They really don't need much, it lasts a long while in the gizzard. I don't keep grit out all the time, I toss a few handfuls out maybe once a month, maybe more or less. I do know my birds didn't get any grit for at least 3 months this summer when I was first diagnosed with leukemia and in the hospital. No one died, they continued to flood us with eggs so it must have been alright. Still have probably 2/3 of that bag. It's a local brand crushed granite for chickens, pretty fine crush. Smaller than peppercorns by quite a bit.