They seem to be fairly durable. I've had them tip over on the bathroom countertop (some sort of artificial stone) and kitchen counter (granite) and so far no cracks or chips. I have owned thicker bottles, but those were simply the bottles an herbal supplement came in. I haven't been able to find really thick bottles that I can purchase. But these do just fine. Not the thickest glass I've ever seen, but certainly durable enough. Haven't dropped from any height, just tip over. And haven't dropped onto the lip of the opening. Hope this helps.