# Fuzzy Math

Hello Everyone,

I’m back again with another question concerning an English Special/Best/Premium Bitter recipe from “Brewing Classic Styles”. The recipe, as it appears in the book, is as follows:

“I’m Not Bitter, I’m Thirsty”
OG: 1.047
IBU: 30

9.5 lbs. British pale ale malt
.5 lb. Aromatic (20L)
.5 lb. Crystal (120L)
.25 lb. Special Roast (50L)

1.2 oz. Kent Goldings for 60 min.
.5 oz. Kent Goldings for 20 min.
.5 oz. Kent Goldings for 1 min.

Today I downloaded the trial version of BeerSmith 2.0, and entered the above recipe to help get acquainted with the software. Much to my surprise, after entering the recipe, the OG and IBU numbers came out as follows (BeerSmith numbers in parenthesis):

OG: 1.047 (1.058)
IBU: 30 (16.7)

Both well outside the guidelines for a Special/Best/Premium Bitter.

When I adjust the OG and IBU numbers to match the recipe, the ingredient amounts are changed as follows (again, BeerSmith numbers in parenthesis):

9.5 lbs. (7 lb 11 oz.) British pale ale malt
.5 lb. (.4 lb) Aromatic (20L)
.5 lb. (.4 lb) Crystal (120L)
.25 lb. (.2 lb) Special Roast (50L)

1.2 oz. (1.78 oz) Kent Goldings for 60 min.
.5 oz. (.74 oz) Kent Goldings for 20 min.
.5 oz. (.74) Kent Goldings for 1 min.

I’ll freely admit that I got these numbers after working with the software for all of a half hour, but it left me wondering how the numbers could be so far apart, with BeerSmith calling for less grain and more hops.

I’m hoping that someone who has experience with the program could let me know if I’m not using/understanding the software correctly, or if the recipe is somehow incorrect in the book. I’m hoping to brew this weekend and would like to know which set of numbers to go with.

As always, thanks for your consideration!

It’s almost certainly because you have (1) the mash efficiency and (2) the hop utilization, or alpha acid levels, or both, in BeerSmith set to something other than what the recipe assumes. IIRC all the recipes in BCS use 70% efficiency, so your efficiency in BS is probably set to something like 85%. For the IBU estimates, check to see if you’re using the same correlation as the recipe (Tinseth, Garetz, Rager, etc.). Essentially, both answers are “right”, they’re just working from different inputs.

Disclaimer: I have no experience with BeerSmith.

I agree with a10t2. Your efficiency per BeerSmith looks very high, so unless you know from experience that your efficiency is truly going to be that high, I would assume Jamil’s recipe is closer to being accurate. With the hops, Jamil has stated many times that he uses the Rager formula. Personally I use Tinseth, as I know Rager tends to be way off on IBUs at low levels. The 30 IBU level is probably indeed wrong, so you may want to increase your hopping per BeerSmith. But don’t reduce the malts per BeerSmith. Make sense??

Thanks very much for the feedback.

After looking into and adjusting some of the profile settings (I specified Tinseth), the numbers are starting to look better. While the software is fairly intuitive, I think I still have a bit of a learning curve to go through, especially in regard to the mash details. At this point, I think I may know just enough to be dangerous. When using the book’s recipe numbers, the specs currently like like this (BeerSmith in parenthesis):

OG: 1.047 (1.057)
IBU: 30 (31.1)

One thing that both of you mentioned, and that I do see, is that the Estimated Mash Efficiency is 80.5% (which I cannot adjust) and Overall Efficiency is set at 70% (my setting). The book states that it estimates 70% for its recipes. Given these numbers, could I somehow adjust the software to get closer to the books numbers? I’m guessing a mash efficiency of 80% is probably unrealistic.

If you’re looking to hit those exact numbers and you know your efficiency is much different than 70%, you may want to alter the recipe, but if you are looking to brew a very good beer to that style, or you don’t know your efficiency, I’d suggest you brew that exact recipe this time, and make alterations once you’ve tasted it and you know what isn’t up to your expectations.

Again, I know next to nothing about BeerSmith, but that can’t be true. Brewing software that didn’t let you adjust the efficiency would be all but useless.

Actually, with a single batch sparge and 6.5 gal pre-boil volume, the lauter efficiency is 86%, so you could easily exceed 80% mash efficiency.

Sage advice. At this point I’m sure that the disparity has more to do with my lack of understanding in using the program (as a10t2 suggested) than the accuracy of the recipe published by two of the foremost authors in the beer world.

Brewhouse Efficiency is set in “Profiles” - “Equipment Profile” I think BeerSmith defaults to 75% and 100% Hop utilization.

I don’t know anything about BeerSmith either, but what I do know is that your mash efficiency will always be higher than your overall brewhouse efficiency. When people throw out the generic term “efficiency”, 99% of the time they are talking about overall brewhouse efficiency. Which is what the 70% is that is assumed in the recipes. You should easily be able to hit 70% efficiency. The question is whether you might get up to 80%, which is also easy if you crush and sparge enough.

I plugged your recipe into BS2 @ 70% efficiency and got this:

1.054 SG
27.4 IBUs

Make sure you have the equipment set correctly. I think default is Pot ( 3 Gal/11.4 L) - Extract that will throw your IBUs way off

Thanks again to all of you who replied - I think I’m slowly getting there.

How should one set up the mash profile in BS2 for batch sparging 5 gallon recipes with equal runnings? I think this is my main area of confusion…

Mash Details Tab, Adjust Mash in amount so that Sparge amount is 1/2 of Preboil amount. Also edit your mash profile and check the box for “Use equal batch sizes”. You may also need to check the box and adjust the “Use batch sizes that fill…” percentage

You can adjust the total efficiency on the recipe design tab just to the left of the mash efficiency box-it looks like the default setting uses the same number for mas eff. and total eff. Once you have an idea of the average efficiency of your system, you can enter it in the total eff. box.

Another thing about hose recipes is that they are set up for a (sort of screwy) 6 gallons. If you are plugging the recipe’s grain amounts in and setting the post-boil volume to 5 gallons, that would also help explain the high predicted OG.

Unfortunately, I can’t help you with the Beersmith specifics, because i’ve never used it.

I’m pretty sure JZ’s recipes assume 70% mash efficiency, not brewhouse efficiency which usually incorporates volume losses during transfers to and from the fermenter.

Yes as I recall it’s 70% into the kettle for enough wort to boil down to six gallons.