It would be nice to have a tool to correct pre boil gravity unit's. for example I am shooting for a pre boil gravity of 1.056 with a target volume of 6 gallon's. after taking a gravity reading I have 1.050 and a volume of 6.5 gallons. I know I could use your Dilution and boil off calculator and just figure out how much extra I have to boil off to hit my target OG but that will reduce my target volume. I would much rather make the adjustment before the boil. So taking my example a target gravity of 1.056 - 1.050(the current gravity) + a deficit of 6 gravity unit's per gallon of wort. 6 GU X 6 gallons = a deficit of 36 total GU's. so assuming that DME yields a gravity of 1.043 per gallon or 43 GU's per gallon's. now divide the GU's per gallon you need by the the GU's of the DME. so 36 / 43 = .837 Lb's or 13.44 oz of DME needed to raise the GU's to the target gravity. Your dilution and boil off tool works fine if you over shoot your target pre boil gravity I am wondering why you don't have one to adjust for hitting low....or do you?