Which online calculator is closest to reality for IBU?

Hey guys,

Now I completely understand that estimating IBUs in a finished beer is not very scientific, and I understand that it is merely an estimation.

The reason I'm posting this is because I have always used a few online calculators to estimate IBU just to make sure I am at least somewhat in the right range before brewing. But recently, the IBU results I have been getting from online sources have been drastically different, so I'm not sure which I should rely on as more 'realistic'.

In the past, I used the following tools:

http://www.brewmasterswarehouse.com/brew-builder
and
http://hbd.org/cgi-bin/recipator/recipator

Both above tools put me in a VERY close range.

Then recently I started using 'Beer Calculus' at Hopville.com and noticed that I am getting much lower IBU ratings.

For example: http://hopville.com/recipe/1203782/american-ipa-recipes/markkus-ipa-2

The above recipe shows 57 IBU in Beer Calculus, brew builder gives me 73 IBU and recipator gives me 90+ IBU.

I want something in the 66 IBU ra nge. So now I'm not sure where I stand.

I guess I could always break out the brewing books and calculate it, but who knows if that will be any closer to reality.

Any suggestions or tips?

Thanks for your time!

 

This may be very obvious, but just wanted to make sure. Are you sure the various apps are using the same AA% for the various hops? I know they all default to values and those values may not be the same.

 

I have found the same thing as you and had a series of beers that were underbittered because of it. For the past year or so I have started calculating them myself using the formulas from Ray Daniel's book. It's a bit complicated and takes some time but my bittering is now consistant. Even if my calculations are not the "right" ones, I know what "my" IBU calculations taste like and can adjust my recipe from that. My calcultor has become one of my most important brewing tools.

 

This comes up alot, when folks compare programs head to head.

A couple of the biggest issues that cause consternation to folks, especially if they compare programs, or if they take for example a recipe from byo or someplace and input it, and find differences have to do with batch size settings and which IBU formula the software is defaulting to.

The final volume of a lot of Palmer and Jamil's recipes, and some of them in magazines are usually 5.5 or 6 gallons whereas most of the time we write recipes for the standard 5 gallon recipes. That often accounts for differences between what we might input in software. Make sure the final volume is matching.

The other thing is, that there's several different calculations used to figure out IBU. And they give different numbers. Somewhere in either a book or on the software it should tell you what the default setting is, and even give you the option to change it to match. But often they don't make it obvious.

Here's an explanation of how Beercalculus calculates it from their Hopville Blog for example;

IIRC beersmith is defalted to tinseth (maybe). So comparing the two in terms of IBUS is going to show up differently.

One of the most recent thread discussing this is here. http://www.homebrewtalk.com/f84/different-ibus-provided-different-software-218066/

The other thing has to do with the efficience a given recipe was created with and the efficiency setting in the particular software. 75% is usually the default in the software, but a lot of folks, especially people who have their systems dialed in may have a higher or lower efficiency setting in their native software, so the anticipated og and fg may be different.

None of these are the software, or mean that one software is better than the other. Often it's the user's own settings that are off.

But in terms of accuracy, they're all accurate, you might think of it simply being that they're in different languages....as long as you stay consistant in using one over any other it will be right.

But in reality it's all arbitrary anyway...they're just numbers. I think a better analogy than what I posted above would be instead of languages think about Fahrenheit vs Celcius or Brix vs specific gravity, they're valid and accurate scales. Just present the same "data" differently.

 

Thanks everyone for responding!

I learned early on how important the volumes were to IBU calculations so I'm always careful of that. What I missed (or rather dismissed) was the AVG boil volume. I didn't understand what that represented until I saw it explained in the thread Revvy linked.

I tend to build my recipes around a 7 gal. boil, but actually boil 3.5 gal. with half the extract to get somewhat equivalent hop utilization. I don't know if this is a good idea or not but it was easier for when I used brewbuilder since there was no way to specify late extract additions. I'm going to try beer calculous with the late addition option and my true boil volume and see what I come up with.

The last pale ale I made seems much more bitter than I was anticipating. I don't mind so much but it's difficult to predict recipes this way.

I just put 6.5 as my boil AVG in Beercalculus and got an IBU estimate of 107 IBU. Evidently this will take some more thought and tweaking for me. As long as I can predict IBUs consistently and have my own "tongue vs. IBU number" chart in my mind, I'll be a happy camper.

Thanks again guys! Great explanation! Much appreciated!