# Does BU = IBU

### Help Support Homebrew Talk:

#### kruserm

##### Active Member
I have a recipe that is calling for a hop addition of 5.1 BU columbus, is this the same as 5.1 IBU columbus? If not is there a conversion to get from BU to IBU?

I am using Beersmith, is there way enter the IBU have it calculate the ounces of hops needed?

#### weirdboy

##### Well-Known Member
Yes BU == IBU.

However, the 5.1, when you say 5.1 Columbus, is NOT IBUs. That is percent Alpha Acid or %AA for short, which expresses the bittering potential in the hops.

The way Beersmith calculates the IBUs for a recipe depends upon the amount of hops, the %AA, the gravity of the wort, and how long the hops are boiled in the wort. So no you cannot just enter the IBUs you want and have it calculate the amount of hops, because there more more variables necessary.

However, in Beersmith it's really easy to just play around with the boil times and amounts of hops to see how that affects the IBUs in your recipe.

OP
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#### kruserm

##### Active Member
Well the recipe calls for:

5.1 BU of Columbus
3.7 BU of Simcoe
etc.

Do you still think they are referring to %AA or IBU?

#### Yuri_Rage

##### Gritty.
Post the entire recipe, including the intended style, and we may be able to help a bit better.

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#### kruserm

##### Active Member
The original recipe is:

50% pale 6-row
50% wheat

10 mins after boil
3 BU N. Brewer
5.1 BU Hallertauer

#### Yuri_Rage

##### Gritty.
That recipe is extremely incomplete. Is it supposed to be a hefeweizen?

#### danculwell

##### Well-Known Member
1 oz of 1AA Hops ==1 BU
so...
x oz of say 6AA Hops = 3 BU
x=.5 oz of hops

if the AA was 3 then you would need a full ounce.

Does that make sense? They list it that way because your ounce of Cascade might have more AA than my ounce of Cascade.

#### JiveTurkey

##### Well-Known Member
If there are no weights associated with the hops, then BU likely means HBU (Homebrew Bittering Units), which is weight of hops (in ounces) multiplied by AA%. AA% without weight is incomplete; you have to know how much of the actual hops are going in.

HBU is a handy unit because it accounts for the fact that the AA% can change from year to year. The recipe tells you what HBU you're shooting for and you should know the AA% of the hops, so for the Columbus in the recipe:

5.1 HBU = 14 AA% (or whatever yours actually is) * x oz.
x = 5.1 / 14
x = .36 oz.

This also helps when substituting different types of hops in the recipe. If you keep the HBU and the time it is added the same, then you should get the same IBUs at the end. However, the aroma/flavor profile (obviously) and strength (less hops = less aroma/flavor, though different varieties have different levels) will change.

Also, HBU = AAU (Alpha Acid Units, which is what BYO magazine uses).

Edit: In the recipe, the BU may mean IBU if the recipe came from a printout. The contributions to IBUs may have been calculated by individual hop. However, this doesn't tell you anything about the time it's added, its weight, or AA%, though I guess one could use a program to find something that works. 8.8 to 10.5 total IBUs is relatively low (depending on style).

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#### kruserm

##### Active Member
That recipe is extremely incomplete. Is it supposed to be a hefeweizen?
Yuri, the recipe is incomplete I was just going off memory and was just giving enough info so I could know if BU = IBU.

#### david_42

##### Well-Known Member
Some countries use BU instead of IBU. Since it's a hefeweizen, those numbers really could be IBUs and not AAU.

if you've got a chance, the complete recipe would be good.

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#### ajf

##### Senior Member
Thanks for all your help, like what most of you have already said BU = IBU. I found a BYO article to confirm this as well.

Sometimes in brewing literature IBUs are referred to simply as Bitterness Units (BU), but the two terms are the same and are interchangeable. For the sake of simplicity the term IBU will be used here.

http://***********/stories/recipes/...p-soup-figuring-bitterness-ibus-aaus-and-hbus
I'd agree that the BYO article is right, but it is prefixed with "sometimes"
In this instance, I would think that danculwell is right.

-a.

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#### kruserm

##### Active Member
Here is the recipe, it is an American Pale Ale.

86.05% Pale Malt 2 row
9.3% Crystal Malt 60L
4.65% Cara-Pils
2.4 BU of Magnum 60min
10.7 BU of N. Brewer 30min
19 BU of Cascade 10min
2 BU of Cascade Whirlpool

This is a total of 34.1 BU do you think this is the same as 34.1 IBU?

#### weirdboy

##### Well-Known Member
That sounds like IBU; it's in the correct range for a typical APA.

However, the first addition (Magnum) is suspicious to me. 2.4 IBUs for 60 minutes boil would be a very, very small addition. So small as to be difficult to measure for a 5 gallon batch.
On the other hand 19 IBUs of Cascade at 10 minutes sounds unreasonably high.

Aha! I think maybe the problem is you have the times reversed on your additions.

When you specify the time for hops additions, the minutes indicate how long BEFORE THE END OF THE BOIL you put them in the pot.

I don't know how long the boil is in this case, but I'm guessing 60 minutes, which means when you add the Magnum, you are doing so at the end of the boil, which would account for the low IBUs. However, if that's true, the first Cascade (~1oz) should be in for the full 60 minutes, though.

If that's not the case, though...well I dunno 2.4 IBUs from 60 minutes of Magnum is...a very very small amount of Magnum. Like, less than 1/10th of an ounce.

#### AiredAle

##### Well-Known Member
This could be a hopburst recipe in which the majority of the bittering hops are added near the end of the boil to give a smoother less lingering bitterness, and a lot of hop flavor. Search hop bursting on this forum for more information. Though I agree, a 2.4 BU addition is a pretty miniscule one.

#### david_42

##### Well-Known Member
2.4 BU of Magnum 60min
This makes me think it's AAU, because otherwise, we are talking about a gram or two.

On the other hand, expressing flavor and aroma adds in BU or AAU is odd.

If it was AAU, then the ounces would be something like:

0.17 oz Magnum @ 60
1 oz NB @ 30
3 oz Cascade @ 10
1/3 oz Cascade in the whirlpool (or flame out)

Not unreasonable for a hop-burst APA.