I was thinking about this again and I realized that in order to make such calculations
completely accurately also requires one to know the degree of fermentability of the wort being used as a primer, and since the batch used as a primer has not yet finished fermenting, we can't know the percentage of attenuation. I think a calculator could be used to make a rough estimate of the amount needed for priming by permitting a user to enter a figure based on past experiences with that or similar recipes and yeast -- in the same manner that we enter a figure for attenuation when creating a recipe even though we can't know for certain what the final attenuation will be. In any event, I can't imagine that even a major deviation between the estimate and actual attenuation could cause bottle-bombs, so I'd think that the worst that could happen would just be some slightly over-carbonated beer. For instance, if you estimate attenuation to be 75% and it turns out to be 90% (which would be really weird), you would actually have added 20% more fermentables than you expected, which means a 20% greater volume of CO2. Unless you are already shooting for a REALLY high carbonation to begin with, I can't see that as a risk of bottle-bombs. Then, on your next batch, you make an adjustment. Of course, I'm not sure that the effects of 'kraeusening' are worth all the trouble, but I've never tried it so I don't know how much it can improve a beer.
EDIT/P.S.: Also, if the data for such calculations are included on the 'Carbonation' tab for a recipe, it could be saved, and then updated with the correct attenuation figure and exact volume of beer that was bottled (this is also an estimate while still in the fermenter due to trub), and then you could know fairly accurately the precise level of carbonation for future reference.
Also, it would be convenient if BTP would include a list of the ranges of carbonation which are appropriate for each style; I realize that the BJCP Style Guidelines do not yet include that, but the information is out there. We discussed this here at the Hop Vine back in January of '07; here is the link:
http://www.beertools.com/forum/viewtopi ... t+creative
Also, here is a link to the TastyBrew calculator which gives a range for each style:
http://www.tastybrew.com/calculators/carbonation.html
Back to 'kraeusening', if the calculations were made easier by BTP, I'm sure there would probably be an increase in the popularity of its use, and like I said -- it would put BTP way ahead of everyone else.
Cheers.
Bill Velek