I'm really stuck on this conversion efficiency calculator. I have a recipe with an OG of 1.057 and it expects my pre-boil gravity to be 1.042. If I enter the expected value of 31L into the volume and 1.042 in the gravity field, it gives me 75% conversion efficiency. Is that correct? According to Braukaiser, if I'm getting under 95% conversion efficiency, I've got a problem. Correct? I just don't get the Mash Water Volume I'm supposed to enter into the calculator. The FAQ says: What exactly does this mean? In this session, for a 3L/kg mash thickness I need 18L of water. The Expected Value is 31L, so where does this extra 13L come from? Sparge water, right? And that's what the Mash Calculator calls "Mash Remaining". Ok, but again, if I enter 31L and my expected gravity in the kettle of 1.042, my efficiency is 75%. Is that what you expect my efficiency to be? I have to enter a gravity of 1.052 to get a 95% conversion efficiency. But if I start the boil with 1.052, I'll way overshoot my target OG of 1.057. I know all about the consistency is more important than efficiency. I'm just trying to understand these calculators. I've used Brewer's Friend for 5 batches now and am ending up with 66% brewhouse efficiencies but I look at recipes on Brewer's Friend and no recipe is showing a brewhouse efficiency that low. I used to do my own math for brewhouse efficiency and I was averaging 74% brewhouse efficiencies. My math and your math don't agree and I'm trying to figure out what is correct. What am I misunderstanding?