Maybe I just don’t know where to look, but there doesn’t seem to be a single source for standard homebrewing calculations. Sure I find them on the Internet and in books on brewing, but many of them are different and yield close, but not exact results. Is there an AHA or BJCP “sanctioned” or “recognized” set of brewing calculations out there for the homebrewer to use?
I ask because I would like to develop my own spreadsheet application for recipe design and result estimations. I know there’s a ton of software already written, but even the commercial software packages results seem to vary.
They vary b/c most of them are just estimations. Hop utilization, for example, depends on many more factors than boil time and wort gravity. As a result each of the brewers who came up with a formula found slightly different results. I’d pick one and stick with it.
The only real standard we have is the ASBC (American Society of Brewing Chemists) or EBC (European Brewing Convention) and even those official bodies don’t necissarily agree on everything. At least they are close. You can buy books where the standards are defined, but those are expensive and not necessarily valuable to you anyway.
It all depends how complicated you want to make it and how complicated it has to be. Given the precision at which we measure during our brewing process highly accurate formulas might be moot anyway. I suggest that you look around on the web and in the literature (Designing Great Beers might be a good start). If you find differences check how big the difference is and if the authors are making different assumptions.