Help With IBU Calc

[danath34]

I am using both Brew Assistant and BrewR apps on my android to formulate the same recipe, and both are giving me (drastically) different IBU values. Can anyone more experienced than I tell me which is a more realistic number for the amount of hops in my recipe?

Both use the following:

1.0 oz Cluster, 60min, whole, 6.5% Alpha
1.5 oz Cluster, 5min, whole, 6.5% Alpha

3gal boil, 5gal final vol.

BrewR gives me a calculated 47.7 IBU, though not sure which method it uses.
Brewing Assistant gives me 13 IBU (tinseth), 23 IBU (rager), and 17 IBU (Garetz)

As you can see, these two values are very different. Which can I believe more?

 

[Psycotte]

Would really need the rest of the recipe to do the calcs. If you post I will have a run at it.

 

[danath34]

thanks for the reply.

The recipe can be seen here:
https://www.homebrewtalk.com/f39/critique-newbies-first-recipe-452548/#post5807927

 

[opiate82]

a.) I would believe the lower numbers more. 47 IBU's seems way to high for a 1oz 6.5%AA 60 minute addition.

b.) Don't put too much faith in any of the calculators. Testing has shown they can be way off from the actual measured IBU's in a beer. Since most of us can't afford to lab test each of our brews if we want an IBU estimate we are stuck with the calculators, but experience and some common sense will give you just as a good of an idea of the bitterness of your brews as these calculators will.

 

[twistr25]

Did you end up dropping that 3 pounds of DME?

 

[twistr25]

Either way - I came up with ~16 IBUs if the extra DME was added, which by the way gave me an OG of 1.095, so not too high. And ~24 IBUs with the DME not added, and an OG of 1.070.

 

[danath34]

a.) I would believe the lower numbers more. 47 IBU's seems way to high for a 1oz 6.5%AA 60 minute addition.

b.) Don't put too much faith in any of the calculators. Testing has shown they can be way off from the actual measured IBU's in a beer. Since most of us can't afford to lab test each of our brews if we want an IBU estimate we are stuck with the calculators, but experience and some common sense will give you just as a good of an idea of the bitterness of your brews as these calculators will.

That's about what I figured. I'm sure after a few more batches I'll have a good intuition on how much bittering comes from a particular hop schedule, but I haven't developed this yet. Thanks for the input. I'll keep it as is because the lower-teens is where I was shooting for the IBU.

Did you end up dropping that 3 pounds of DME?

Yes. I did have it at 6, because I mistakenly thought the NB kit had 3lb of LME, but I dropped it to 3lb DME when I found out the kit actually had 6lb. I know 3lb DME is not equal to 3lb LME, but this was a simple change, and still gets me in the general area of my desired OG.


Thanks for the input, guys. Now as soon as I can source a cheap fridge to build my fermentation chamber, I'll get this brewing!