Calculating a Brew
With a pencil, paper & calculator
There are great programs to help you calculate a brew available for downloads. I use Beersmith (thanks Brad!) but when I started brewing I did it by hand calculations, and it”s fun to go back every now and then and see how it all pencils out. Brewer Geeks will like this.
MALT
First, I do the grain bill. I calculate it based on the % of each type of malt adding up to 100%. Let’s do a simple 5-barrel batch of a dark mild. Here is how I write it up.
2 Row 72%, Maris Otter 7%, Carapils 5%, Victory Malt 5%, 120L 5%, Chocolate malt 4%, Black 2%. Brew is 5 Bbls or 586 liters. 10P, 20 IBU using Nugget Hops at 16% Alpha acid.
10P. = 26.89 pounds per barrel. This is from a table in The Practical Brewer, see chart on the bottom. I have the current addition but also the original (signed) first addition from 1946! The numbers are the same. So, 26.89 X 5 BBLs equals 134.45 pounds. But that’s just the beginning. You take each malt (2 row at 72%) multiplied by the 134.45. That gets divided by the malt yield times brewhouse efficiency.
Siebel Institute gives a malt yield of base malt at 66% ( you can calculate your own system). This gets multiplied by brew efficiency. I use 90%. So .66 X .9 = .594. It would look like this for 2 Row
(.72)(134) / (.66)(.90)= 162# of two row.
Do this for each malt, however yield will drop. Use .64 for specialty malts, and .55 for dark malts. When you are done, this is your grain bill for 5 BBLs of 10 degree Plato wort.
BITTERING HOPS
We plan on only 20 bittering units in one addition into the boil. This formula goes like this.
IBU X .001 X liters of wort / hop bittering efficiency X alpha acids
Let me break that down. 20 bittering units get multiplied by a dilution factor of .001. This then gets multiplied by the alpha acid of the hops you are using. The bottom line you divide by is the efficiency of your equipment in utilizing the bittering of your hops. Just use .30 to start, but in my original numbers from Siebel I used .22, however my beers were more bitter than my calculations. If you send you beer to have the bittering units analyzed, you will come up with an exact number for your equipment. For our example .30 will work. This .30 gets multiplied by your alpha acids. Here is how this will look on this brew.
(20)(.001)(586) / (.30)(.16)=11.72/.048=244g hops or 8.6. oz.
Let’s say you wanted to divide up your bittering hops 50/50 with different hops at different alpha acids. You would use the same formula but change the bittering units to 10 each and also change out the alpha acids so each line represented the hop variety. Then your hop calculation. will look like this.
Nugget (10)(.001)(586) / (.30)(.16)=122g hops or 4.3 oz.
Northern Brewer (10)(.001)(586) / (.30)(.098)=199g hops or 7 oz.
I know I write about the business of brewing a lot, but I am still a brewer at heart, and this sort of thing is just fun. You can play with this. The numbers work out if you know your malt yield, brewhouse efficiency, and hop efficiency. In the meantime you can simply plug in the numbers here and see how it compares to what you are doing.
You can use this if you are thinking about stepping up a 5 gallon batch to a 7 barrel batch, or higher. I used this to go from 6 barrels in one brewery to 20 barrels when I started the Palisade Brewery. It worked out just fine. Get out your pencil and calculator and have some fun.
