3 beer recipe calculators. 3 very different results.

So, let's talk about beer recipe calculators for a second. I'm looking into brewing an extract recipe for a Black IPA. After poking around these here forums, I found a recipe that looks right:

https://www.homebrewtalk.com/f39/extract-recipe-black-ipa-161100/#post1859836

Here it is for convenience:

7.5 lbs light DME (3 lbs. at start of boil, 4.5 at end)
12oz. victory
12oz. crystal 60L
6oz carafa II
6oz chocolate

2oz centennial 60
1oz centennial 30
1oz centennial 20
1.5oz cascade 15
1oz cascade flameout
1oz willamette flameout
1oz cascade dry
1oz willamette dry

Pitched 2 vials WL001 California Ale
OG: 1.077
Est. FG: 1.017
ABV: 7.8%
Color: 27 SRM
Bitterness: 74 IBU
(SRM and IBU calculations by recipator)

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I wanted to do a little hop substitution and figure see how it would effect the IBU's. So, as a first step, I out the recipe into BeerSmith and came up with this:



...say whaa? Why does Beersmith show such a different color and bitterness reading?

So then I tried two more recipe calculators, plugging in the exact same recipe:

Black IPA | BrewersHub - Shows 153 IBU and 31 SRM.
View Recipe | Brewer's Friend - Shows 107 IBU and 29.45 SRM.

Am I completely screwing something up, or are beer calculators really this different?

Also, I'm a new brewer, so if I royally messed up the recipe entry or am completely missing some concept- tell me!

Thanks

I assume the original recipe was for a partial boil? And those software programs have a heck of a time with partial boil IBUs and the way they calculate them. And in Beersmith, a late extract addition makes the IBUs even higher in the software. Youve got a bigger boil (6+ gallons) plus the late extract addition. IT can't really figure those IBUs. So, that's why.

But that recipe has three ounces of bittering hops (2 at 60 minutes, and 1 at 30) so that's a LOT of bittering.

Still, the most IBUs you can reasonably get into solution is about 100 IBUs so don't be too scared when you go over 100 because that's just in theory. Still, that will be a pretty darn bitter beer.

The color is about the same- there is really no difference between 27 and 28 SRM.

Given that the recipe calls for 7.5lbs of extract, I'd think it's safe to say it's an extract + specialty grain recipe. Though I admit being confused by this part:

7.5 lbs light DME (3 lbs. at start of boil, 4.5 at end)

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Do they really mean "add 4.5 lbs of DME in at flameout"? Seemed odd to me.

Going back to beersmith, when I alter the recipe so that all 7.5lbs of DME are in the boil for a full 60mins, the IBU's do drop down to 127. Still a far cry from what the original recipe says it should be- 74 IBU.

And it also still doesn't account for this calculator saying it should be 107 IBU's or this one saying 153 IBU's.

So I understand that how long the DME is boiled will effect IBU's- I just don't know why all the calculators still differ so wildly.

jeremydgreat said:

Do they really mean "add 4.5 lbs of DME in at flameout"? Seemed odd to me.

Going back to beersmith, when I alter the recipe so that all 7.5lbs of DME are in the boil for a full 60mins, the IBU's do drop down to 127. Still a far cry from what the original recipe says it should be- 74 IBU.

And it also still doesn't account for this calculator saying it should be 107 IBU's or this one saying 153 IBU's.

Click to expand...

Yes, you add the second bunch of DME at flameout. BUT not if you're actually boiling the full amount of 6+ gallons at the beginning.

The late extract addition is a great tool for those who have small pots and must boil only a portion of the extract. They add the extract at the end. It keeps the color lighter, and the beer has a less "cooked extract" flavor. It's not necessary if you're boiling 6+ gallons from the beginning, as your Beersmith screenshot indicates.

jeremydgreat said:

G
Going back to beersmith, when I alter the recipe so that all 7.5lbs of DME are in the boil for a full 60mins, the IBU's do drop down to 127. Still a far cry from what the original recipe says it should be- 74 IBU.

And it also still doesn't account for this calculator saying it should be 107 IBU's or this one saying 153 IBU's.

So I understand that how long the DME is boiled will effect IBU's- I just don't know why all the calculators still differ so wildly.

Click to expand...

Like I said, those calculators can't deal with IBUs over 100 anyway, so the difference between 127, 107, and 153 is insignificant.

But because your original recipe states 74 IBUs, I'd try just for fun to use Beersmith again. Change the "boil volume" to 2 gallons, and put all the DME in the first group of boiling 60 minutes. And see what that does.

One thing that could be different between the calculators is the method of calculating bitterness... Rager, Tinseth or Garetz are the big ones.

Yooper said:

Like I said, those calculators can't deal with IBUs over 100 anyway, so the difference between 127, 107, and 153 is insignificant.

But because your original recipe states 74 IBUs, I'd try just for fun to use Beersmith again. Change the "boil volume" to 2 gallons, and put all the DME in the first group of boiling 60 minutes. And see what that does.

Click to expand...

Okay, back to beersmith: I've put all 7.7lbs of DME in at 60min. Messing around with the water volume I get...

Batch size: 5 gal
Est Pre-Boil Vol: 6.48 gal
Resulting IBU: 127.4

Batch size: 5 gal
Est Pre-Boil Vol: 3 gal
Resulting IBU: 73.9

Crazy! I mean, does it actually work that way? I always thought it didn't really matter if you boiled with 3 or 4 or 5 gallons of water- as long as there was 5gal in the carboy when you dumped the yeast in.

The wort gravity affects hop utilization. A higher gravity will have less.

If you do a three gallon brew and dilute to 5 you will have less IBUs than if you boiled at full volume.

Brewsmith said:

The wort gravity affects hop utilization. A higher gravity will have less.

If you do a three gallon brew and dilute to 5 you will have less IBUs than if you boiled at full volume.

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For grains, I could see how that's possible. But for hops, it's hard to imagine that the same amount of hops will yield nearly half the bitterness if they are boiled in 3 gallons of water versus 5 gallons. I mean maybe it is true!?

jeremydgreat said:

For grains, I could see how that's possible. But for hops, it's hard to imagine that the same amount of hops will yield nearly half the bitterness if they are boiled in 3 gallons of water versus 5 gallons. I mean maybe it is true!?

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For hop alpha acids there is a limit to how much can be dissolved in water (it works out to be about 100 IBUs in bitterness). So if you have a lot of bittering hops in 2.5 gallons and get to 100 IBUs, then dilute to 5 gallons you end up with 50 IBUs. If you do a full boil more alpha acids dissolve so the same recipe could be 100 IBUs if you had enough bittering hops.

cshamilton said:

For hop alpha acids there is a limit to how much can be dissolved in water (it works out to be about 100 IBUs in bitterness). So if you have a lot of bittering hops in 2.5 gallons and get to 100 IBUs, then dilute to 5 gallons you end up with 50 IBUs. If you do a full boil more alpha acids dissolve so the same recipe could be 100 IBUs if you had enough bittering hops.

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Yep, that's the jist of it. Lately, new thinking has said that wort gravity has very little impact on the hops utilization. But it's been said all along (and still today) that there is a theoretical maximum of hops oils that can isomerize, generally 100 IBUs.

If you make 5 gallons of 100 IBU wort, then you will have a 100 IBU beer. But if you make 2.5 gallons of 100 IBU wort and top off with 2.5 gallons of 0 IBU wort (water), you get a maximum of 50 IBUs in the beer. Not due to the lack of hops, but instead that the wort can only "hold" so much hops oils in solution and they don't isomerize above about 100 IBUs.

That's why it's so tough to make a great IPA with a partial boil. It's just not possible to get more than about 50-70 IBUs in a partial boil.

Wow. I just learned a lot about hops. Thank you. I swear, if chemistry had been taught to me like this in college, maybe I would have cared more.

Wikipedia: Isomerisation - Better beer through science. haha.

What you're explaining sounded unbelievable (or at least unintuitive at first) at first, but makes total sense now.

Jeremy, I'm in the same boat as you. I want to make an IPA with a high ibu but apparently it's just not too feasible with partial boil set up. Looks like I need a bigger kettle.