As all have said 40 is the accepted normal "far". I think anything past thirty is to far myself cause under thirty and the odds are in the hunters favor, over thirty and the more "anything" can happen. But if you want to know how far is it lethal I do not know. The farthest I have ever seen anyone kill any thing with an arrow was on TV once were a guy was killing one of those dumb caribou, the ones that stand there and watch as the hunter stands up and aims in plain sight! The guy had a compound and hit the thing at seventy yards! Now it was TV so anything is possible but it looked real, but I would never do it!