IBU HBU - conversions...

[Derric]

OK... this has been in the back of my mind for a while. If you have IBU,
how do you know how much of a given type of hops to use in a recipe?
With HBU it is trivial to do.

Regarding IBUs, it seems they are mainly good for "talking" about
bitterness in beer - ie., I understand it is a standard for comparing
various beers to each other and I see its usefulness there.

However, at the hands on level, as far as brewing and recipes, etc.,
HBUs seem much more practical and I used them exclusively.

So... is there a forumla to take IBUs, hops AAU, boil time, batch
volume, etc. and convert it to ounces of hops to use?

Derric

[John 'Shaggy' Kolesar]

Post by Derric
OK... this has been in the back of my mind for a while. If you have IBU,
how do you know how much of a given type of hops to use in a recipe?
With HBU it is trivial to do.
Regarding IBUs, it seems they are mainly good for "talking" about
bitterness in beer - ie., I understand it is a standard for comparing
various beers to each other and I see its usefulness there.
However, at the hands on level, as far as brewing and recipes, etc.,
HBUs seem much more practical and I used them exclusively.
So... is there a forumla to take IBUs, hops AAU, boil time, batch
volume, etc. and convert it to ounces of hops to use?

Yes there is, but the formula is more complex than it is for HBU.
HBU is nice in that it's very simple, but it's also not very accurate.
IBUs are much more accurate, but not very simple.

IMO, I wouldn't try to calculate IBUs by hand. Use any of the software
recipe programs to do it for you, most of the ones I'm familiar with
all do IBU calculations.


John.

[Derric]

Post by John 'Shaggy' Kolesar
IMO, I wouldn't try to calculate IBUs by hand. Use any of the software
recipe programs to do it for you, most of the ones I'm familiar with
all do IBU calculations.

Thanks John... I have some of them and I'm a "computer guy," but
usually just do homebrewing things by hand! :) I don't know why
that is...

I did find some of the formulas on the St. Pat's homepage via Google...
I'm looking at them now.

Derric

[Dan Listermann]

I use an abbreviated method of calculating IBU which is accurate enough for
most homebrewing.

IBU = Alpha acid * Ounces * 20 / gallons.

This is for a 60 minute boil. Scale the "20" constant for less time.

For five gallon batches it is IBU = AA * oz * 4. This can be done in your
head.

Compare this to software calculations and you will find that it is close
enough to use for someone who has no means of directly measuring IBUs.

Oh, don't forget that ANY such calculation, no matter how complex or
"accurate," is a prediction of bitterness, NOT a measurement.

Dan Listermann

Post by Derric
OK... this has been in the back of my mind for a while. If you have IBU,
how do you know how much of a given type of hops to use in a recipe?
With HBU it is trivial to do.
Regarding IBUs, it seems they are mainly good for "talking" about
bitterness in beer - ie., I understand it is a standard for comparing
various beers to each other and I see its usefulness there.
However, at the hands on level, as far as brewing and recipes, etc.,
HBUs seem much more practical and I used them exclusively.
So... is there a forumla to take IBUs, hops AAU, boil time, batch
volume, etc. and convert it to ounces of hops to use?
Derric

[Derric]

Post by Dan Listermann
IBU = Alpha acid * Ounces * 20 / gallons.
This is for a 60 minute boil. Scale the "20" constant for less time.
For five gallon batches it is IBU = AA * oz * 4. This can be done in your
head.

Thanks Dan! That's useful.

What prompted my question was a recipe that only listed IBU for bittering
- so how many ounces of hops do you use? I continued looking around
and found some other equations. Personally, I'll probably keep using
HBU for recipes, but when a recipe only gives an IBU value for the beer,
this one works:
Ounces of boiling hops = (0.22 * IBU) / AA%
like: 0.22 * 40 / 4.6% = 1.9 ounces.
The constants assumed are: 1 hour boil, 30% AA utilization, 5 gallon
batch, and a typical original gravity (high OGs will change it). The
unsimplified equations allow you to change all those values.

I guess most folks here use software. I do play with various software
but don't really use one right now.

Derric

[bregent]

Post by Derric

Post by Dan Listermann
IBU = Alpha acid * Ounces * 20 / gallons.
This is for a 60 minute boil. Scale the "20" constant for less time.
For five gallon batches it is IBU = AA * oz * 4. This can be done in your
head.

Thanks Dan! That's useful.
What prompted my question was a recipe that only listed IBU for bittering
- so how many ounces of hops do you use? I continued looking around
and found some other equations. Personally, I'll probably keep using
HBU for recipes, but when a recipe only gives an IBU value for the beer,
Ounces of boiling hops = (0.22 * IBU) / AA%
like: 0.22 * 40 / 4.6% = 1.9 ounces.
The constants assumed are: 1 hour boil, 30% AA utilization, 5 gallon
batch, and a typical original gravity (high OGs will change it). The
unsimplified equations allow you to change all those values.
I guess most folks here use software. I do play with various software
but don't really use one right now.

The problem with hbu's is that it doesn't take any utilization factors into
account. So, a beer with 2 ounces of hops has the same hbu's, regardless of
whether the hops were added at 60 minutes or 15 minutes before knockout. IBU's
are slightly more complex to use, but a simple spreadsheet is all you need. If
your hop schedule only calls for one hop addition, then you could probably stick
with just hbu's.

[Derric]

Post by bregent
The problem with hbu's is that it doesn't take any utilization factors
into account. So, a beer with 2 ounces of hops has the same hbu's,
regardless of whether the hops were added at 60 minutes or 15 minutes
before knockout. IBU's are slightly more complex to use, but a simple
spreadsheet is all you need. If your hop schedule only calls for one
hop addition, then you could probably stick with just hbu's.

I see... I generally only worry about the main bittering addition and
ignore the FWH, flavor, aroma, and dry hop additions, if present. When
I enter into software, I do see the different additions accounted for.

Since I tend to overly RDWHAHB when I brew, that simplification has been
acceptable! :)

Another odd (negative?) thing about HBUs is that they are only for a
given batch size. Ie., 10 HBU for a 5 gallon batch. If you double the
batch, the HBU doubles (to 20). The IBU would stay the same for any
quantity of beer. After this discussion and research, I understand this
pretty well, whereas before I had pretty much just ignored it. If you
only make 5 gallon batches with a simple hop schedule you can do that.

Derric

[John 'Shaggy' Kolesar]

Post by Derric
Another odd (negative?) thing about HBUs is that they are only for a
given batch size. Ie., 10 HBU for a 5 gallon batch. If you double the
batch, the HBU doubles (to 20). The IBU would stay the same for any
quantity of beer. After this discussion and research, I understand this
pretty well, whereas before I had pretty much just ignored it. If you
only make 5 gallon batches with a simple hop schedule you can do that.

Plus, HBUs take no account of the type of boil being done. You will get
different IBUs from the same amount of hops depending on whether you do
a full or partial boil. So all grain brewers get different amounts of
bitterness for the same HBU compared to extract brewers.

There are even several different formulas for calculating IBUs that
favour different types of brewers. That's something else to keep in mind
when trying to match up the amount of hops to use for a recipe that only
lists IBUs. Do you know which formula they used? There can be some
pretty big differences between them.

IMO, HBUs are just too simplistic to be very useful. They completely
ignore fairly significant variables. As Dan said though, any formula
for calculating bitterness is just going to be an approximation.
Worrying too much about the differences may just be a waste of time,
since you'll never get it completely accurate without sending your beer
off to a lab for analysis.


John.

[Derric]

There are even several different formulas for calculating IBUs ...
Do you know which formula they used?

No I don't...

Worrying too much about the differences may just be a waste of time,
since you'll never get it completely accurate without sending your beer
off to a lab for analysis.

Understand completely. I certainly don't worry about it... seeing that
recipe made me start wondering exactly how I would figure the ounces of
hops from the IBU. I've got a handle on that now, but it seems it will
necessarily be a "rough" handle anyway.

Thanks!

Derric

[John 'Shaggy' Kolesar]

Post by Derric
Understand completely. I certainly don't worry about it... seeing that
recipe made me start wondering exactly how I would figure the ounces of
hops from the IBU. I've got a handle on that now, but it seems it will
necessarily be a "rough" handle anyway.

It's unfortunate that a lot of recipes don't include enough information.
You see the same issues pop up with all grain recipes that list lbs of
grain but no OG. If you don't know what the author's efficiency was
it's almost impossible to reproduce the same beer from their recipe.


John.

[Denny Conn]

Post by bregent
The problem with hbu's is that it doesn't take any utilization factors into
account. So, a beer with 2 ounces of hops has the same hbu's, regardless of
whether the hops were added at 60 minutes or 15 minutes before knockout. IBU's
are slightly more complex to use, but a simple spreadsheet is all you need. If
your hop schedule only calls for one hop addition, then you could probably stick
with just hbu's.

Great points. I find the main usefulness of HBUs for me is when I'm converting fom
the AA of one batch of hops to another. Since the utilization will be the same
either way, it's an easy way to figure out how much weight you need of a different
AA.

------------>Denny

--
Life begins at 60...1.060, that is.