## HBU & IBU Calculator

The IBU Calculator is an applet, written in Java,
which calculates Homebrew Bitterness Units (HBU) and
International Bitterness Units (IBU) of a given beer.

HBU's are simply the amount of alpha acids in a
particular batch of beer, ie, the amount of hops added times the
percent alpha acid. Each hop addition is calculated separately
then summed to give total HBU's. This calculation is relatively
easy, but is not as useful as IBU's since boil time is not taken
into account.

IBU's are a more useful, and more accurate,
measure of hop bitterness in a beer or wort. However, it is much
more difficult to calculate.

With increased boil time comes increased hop
utilization, ie, the longer the hops are boiled, the higher the
utilization rate and the more alpha acids departed to the wort.
Since the relationship of boil time to hop utilization is not a
constant, calculating IBU's becomes a bit more involved than HBU
calculation. To assist with this, I've taken values from the Hop
Utilization graphs in __The Brewer's Companion__, by Randy
Mosher, and used interpolation to calculate percent utilization
for each hop addition. I then sum IBU calculations for each hop
addition to get the composite, or Total, IBU's.