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5. Designer's Notes

5.1 Grain Calculations

The basic gravity calculation is the sum of all grains' extract times quantity, divided by the batch size. Mashed grains will have their extract modified by the mash efficiency. Steeped grains will use only 1/3 of their extract.

The color calculated is in SRM, not in HCU (homebrew color units). HCU is the sum of all grains' color times quantity, divided by the batch size. This is only accurate for very low color values. It is converted to SRM by multiplying by 0.2 and adding 8.4, for all HCU values over 8.0. It is still very possible to achieve SRM colors above 40 using these calculations.

Final gravity is assumed to be 25% of the OG. Looking through the AHB style guide, this is the same assumption they made. The alcoholic content calculations were derived from Noonan's NBLB, and based on this FG assumption.

5.2 Hop Calculations

Hops are calculated by taking the sum of each hop's quantity times alpha times utilization times 0.75, and dividing by the batch size. This is corrected for the boil gravity with Rager's formula: divide by one plus five times OG - 1.050. Rager's formula was used for simplicity. The utilization factors are based on Noonan's NBLB, since they appear to be the most accurate, but they can be changed by editing the appropriate sections in the file calcdb.


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