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IBU's Tinseth vs. Rager

I was using BrewersFriend.com to put a recipe together to work towards a clone of a GLBC beer which has an IBU of 80. I noticed the 2 different methods of calculating IBUs: Tinseth and Rager. The values weren’t even close (43 Tinseth, 80 Rager). So with these values being so vastly different, is there anyway to know which one I should use outside of asking the brewmaster at GLBC which method they use to calculate their IBU’s?

Here is the hop schedule for reference:
2 oz - Nugget, Type: Pellet, AA: 11, Use: Boil for 60 min
0.5 oz - Mosaic, Type: Leaf/Whole, AA: 12, Use: Boil for 15 min
0.5 oz - Cascade, Type: Pellet, AA: 7, Use: Boil for 15 min
0.5 oz - Mosaic, Type: Leaf/Whole, AA: 12, Use: Boil for 5 min
0.5 oz - Cascade, Type: Pellet, AA: 7, Use: Boil for 5 min
3 oz - Mosaic, Type: Leaf/Whole, AA: 12, Use: Dry Hop for 12 days

Smells like an IPA! Is that hop schedule for 5 gallons, or some other volume? If for 5 gallons, it appears to me that the Rager result is more correct in this case. However I’m sure Tinseth would get you a higher number, so I’m thinking it is the online calculator that is wrong with respect to Tinseth, not the actual Tinseth equation. Tinseth is typically the most accurate, but I think I’d go with Rager in this case, assuming the recipe is for 5 or 6 gallons.

Yep, this is an IIPA and 5gal total volume. Thanks!

Tinseth is more accurate than Rager. However I find that many beer recipes tend to report their bittering using the Rager equation. The problem is when you target a bittering level from one of those recipes and use the Tinseth equation for your brew. Your beer ends up significantly overbittered.

Jamil said it best: Pick an equation and stick with it. Learn the bittering levels you like, using that equation.

I have been using StrangeBrew software for many years with great success – I can always nail my desired IBUs with it. When I pumped your IIPA hop bill into my StrangeBrew software for a 5-gallon all-grain batch and assuming 60 minute boil and 15% crystal malt, it gave me 89 IBU for Tinseth and 110 for Rager. So regardless of actual IBUs, it looks like it’s going to be in the ballpark of “really really bitter”, which I’m sure is what you wanted. I don’t know how brewersfriend.com calculates their IBUs but it seems out of whack. If you must use it, stick with Rager as I said before, but it still might be quite a ways off. You might want to invest in a more reliable software platform such as StrangeBrew or BeerSmith or ProMash or something like that, which are used by roughly 95% of homebrewers.

I actually plugged the same info into BeerSmith and got an even bigger discrepency (though I think I was using lower AA (11%) for Mosiac since neither software seems to have the info on Mosaic). Not really sure what I’m doing wrong here. Here is the recipe as I’m entering it, you can see the Tinseth IBU bolded:

2 lbs Caramel/Crystal Malt - 40L (40.0 SRM) Grain 15.4 %
1 lbs Honey Malt (25.0 SRM) Grain 7.7 %
10 lbs Light Dry Extract (8.0 SRM) Dry Extract 76.9 %
2.00 oz Nugget [13.00 %] - Boil 60.0 min Hop 26.3 IBUs
0.50 oz Cascade [5.50 %] - Boil 15.0 min Hop 1.4 IBUs
0.50 oz Mosaic [11.00 %] - Boil 15.0 min Hop 2.5 IBUs
0.50 oz Cascade [5.50 %] - Boil 5.0 min Hop 0.6 IBUs
0.50 oz Mosaic [11.00 %] - Boil 5.0 min Hop 1.0 IBUs
1.0 pkg London Ale Yeast (Wyeast Labs #1028) [124.21 ml] Yeast -
3.00 oz Mosaic [11.00 %] - Dry Hop 14.0 Days Hop 0.0 IBUs

Beer Profile

Est Original Gravity: 1.091 SG
Est Final Gravity: 1.021 SG
Estimated Alcohol by Vol: 9.2 %
Bitterness: 31.8 IBUs
Calories: 151.6 kcal/12oz
Est Color: 17.8 SRM

Funny… Now I get 79 IBU for Tinseth, and 114 for Rager. I really don’t know what could be causing the discrepancy. It is very clear to me that 31.8 IBU is just plain flat wrong. There’s something fishy going on.

By the way… there’s no way in heck you’ll hit a final gravity of 1.021 with that recipe. You’ll be lucky to get anything below 1.030. To fix that, replace 2.5 lb DME with cane sugar instead. You’ll be glad you did. Then you can hit closer to 1.026, which is still sweet but not quite so much.

[quote=“dmtaylo2”]Funny… Now I get 79 IBU for Tinseth, and 114 for Rager. I really don’t know what could be causing the discrepancy. It is very clear to me that 31.8 IBU is just plain flat wrong. There’s something fishy going on.

By the way… there’s no way in heck you’ll hit a final gravity of 1.021 with that recipe. You’ll be lucky to get anything below 1.030. To fix that, replace 2.5 lb DME with cane sugar instead. You’ll be glad you did. Then you can hit closer to 1.026, which is still sweet but not quite so much.[/quote]

I’ll assume the recipe is closer to the 80 IBU I am going for.

Thanks for the advice on replacing the DME. I assume by cane sugar you just mean regular old table sugar

Are you doing a partial boil, or more importantly does you software assume you are? Hop utilization goes down as gravity goes up, and most beer software attempts to correct for this. A partial boil of a high gravity beer like this will leave you with a REALLY high gravity initially. No idea if that’s what’s up with your software, but its a possibility. See if there’s a box you can check for late extract addition.

It is a partial boil. Beersmith has estimated preboil volume of 2.5 gallons and batch size of 5.0

[quote=“dmtaylo2”]
By the way… there’s no way in heck you’ll hit a final gravity of 1.021 with that recipe. You’ll be lucky to get anything below 1.030. To fix that, replace 2.5 lb DME with cane sugar instead. You’ll be glad you did. Then you can hit closer to 1.026, which is still sweet but not quite so much.[/quote]

Curious why you don’t think this can achieve 1.021. That’s an actual attenuation of 62% and I’m using Wyeast 1028 which has an apparent attenuation of 73-77%. I’m obviously a newb here so just curious if I’m using a healthy starter why the yeast won’t be able to handle the job.

Extract doesn’t attenuate as well as all grain, and you also have 3lbs worth of crystal malts that basically won’t attenuate at all. I don’t know if I would personally substitute an entire 2.5 lbs as suggested, but substituting some malt for sugar will indeed give you a drier beer, and is a common technique for extract brewers trying to make big beers.

Got it. Make sense.

You think 1lb would be enough? Any pointers on if corn or table sugar is better?

Nate42 is right – extract and crystal malts don’t attenuate very well at all. I would use no less than 2 lbs table sugar for this recipe. You can use corn sugar if you want, but table sugar is just as effective and a lot cheaper. If you have read anything anywhere about sugar producing “cidery” flavors, ignore it, it is not true. As an example, the Belgians often use a lot of sugar in their recipes, and they make some of the best beers in the world.

I’m still pretty concerned I’m going to make a beer that’s too bitter cause of something I’m doing wrong in BeerSmith. Can anyone plug this recipe into BeerSmith or some other software to verify that they are getting the same values for bitterness. I moved some of the extract additions to later in the boil (20min). IBU shown is Tinseth.

Style: Imperial IPA
TYPE: Extract

Recipe Specifications

Boil Size: 2.50 gal
Post Boil Volume: 2.21 gal
Batch Size (fermenter): 5.00 gal
Bottling Volume: 4.60 gal
Estimated OG: 1.091 SG
Estimated Color: 15.8 SRM
Estimated IBU: 71.2 IBUs
Brewhouse Efficiency: 72.00 %
Est Mash Efficiency: 0.0 %
Boil Time: 60 Minutes

Ingredients:

Amt Name Type # %/IBU
2 lbs Caramel/Crystal Malt - 40L (40.0 SRM) Grain 1 15.4 %
1 lbs Honey Malt (25.0 SRM) Grain 2 7.7 %
2 lbs Light Dry Extract (8.0 SRM) Dry Extract 3 15.4 %
1.50 oz Nugget [13.00 %] - Boil 60.0 min Hop 4 20.3 IBUs
6 lbs Light Dry Extract [Boil for 20 min](8.0 Dry Extract 5 46.2 %
2 lbs Sugar, Table (Sucrose) [Boil for 20 min] Sugar 6 15.4 %
0.53 oz Cascade [5.50 %] - Boil 15.0 min Hop 7 1.5 IBUs
0.53 oz Mosaic [11.00 %] - Boil 15.0 min Hop 8 2.7 IBUs
0.53 oz Cascade [5.50 %] - Boil 5.0 min Hop 9 0.6 IBUs
0.53 oz Mosaic [11.00 %] - Boil 5.0 min Hop 10 1.1 IBUs
1.0 pkg London Ale Yeast (Wyeast Labs #1028) [12 Yeast 11 -
3.00 oz Mosaic [11.00 %] - Dry Hop 14.0 Days Hop 12 0.0 IBUs

Mash Schedule: Single Infusion, Light Body, No Mash Out
Total Grain Weight: 13 lbs

Sparge: Remove grains, and prepare to boil wort
Notes:

I use an excel spreadsheet I created years ago so take that for what it’s worth, but when I punch in that hop bill/boil gravity I also get 71 IBUs using Tinseth.

I didn’t run the numbers again as I think they’ll stay pretty close to what I had last time, but I just wanted to say that I think your recipe is in good shape now. Hopefully the final gravity will be 1.027-ish. One more thing: Be sure to pitch a lot of yeast. Make a starter, or add multiple packs. This is important to assure the fermentation doesn’t crap out too early. Sorry I didn’t mention it sooner.

Definitely planned on a starter. I just built a stir plate a few days ago so I’m eager to try it out!

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