4 1/2 stars. I really like this app, but it has one problem. This app saves all user entered values with the exception elevation. You will have to memorize your elevation to re-enter it every time. Elevation is the single biggest improvement over all the other calculators so not saving this one value (that will be the most consistent in your calculations) is very unfortunate.
Man's greatest achievement since the pyramids of Egypt! Should be required for every Brewery, Beer Distributor, and Draught Retailer.