New calculator

I've always had difficulty finding a way to predict Pre-Boil Gravity when creating my recipes, so it's a variable I've never really taken into account when I brew. I typically sparge until I have the proper wort volume in the kettle, then do a 60 minute boil, and if my Original Gravity is low or high, then so be it. However, armed with the knowledge of what my Pre-Boil Gravity should actually be, I might have some options to actually hit my Original Gravity instead of guessing. Similarly, if I knew my Pre-Boil Gravity I should be able to calculate a prediction about Original Gravity and make any necessary alterations to achieve my target numbers. September's issue of Brew Your Own magazine has an article by Bill Pierce that sheds some light on boil mechanics and calculations. I used his calculations to create an automated calculator for pre and post boil gravity. If you haven't read his article I think you will find it alone is worth the cover price. My version of the calculator is here.