# Math People - Help Me Calculate My Eisbock ABV

### Help Support Homebrew Talk:

#### CenturyStanding

##### Well-Known Member
Hey everyone,

So, I just bottled a Scottish Ale that I treated like an Eisbock and froze then concentrated in a random experiment I'm trying.

The full beer was about 3 gallons with an O.G. of 1.060 and F.G. of 1.015 for an ABV of 6.0%.

When I froze the beer and concentrated it, I was left with about 2 gallons. The discarded 1 gallon, at room temperature, had a gravity of 1.008. I forgot to read the gravity of the 2 gallons before I bottled it.

So, based on the information, do you know what the F.G. and ABV is of the 2 gallons I bottled? Is there a mathematical way to calculate it?

Thanks in advanced for the help.

#### Killinger

##### Well-Known Member
Is close enough close enough?

If so...

You had 3 gallons at 6% ABV, so, you had 0.18 gallons of alcohol (0.18/3 = 6%). You removed 1 gallon of water. You still have 0.18 gallons of alcohol. 0.18/2 = 9%.

The formula, I guess, should be:

Starting ABV * Starting Volume / Ending Volume

6% * 3 / 2 = 9%

#### remilard

##### Well-Known Member
There is no way to tell exactly without knowing the real extract of the concentrated portion and the other portion.

OP
OP
C

#### CenturyStanding

##### Well-Known Member
Yeah, that's what I figured. In a perfect world, it would be 9%, but then the gravity of my left over gallon should be 1.000.

Oh well, either way I'm sure it'll be delicious.

Thanks for the help.

#### bosco_NJ

##### Well-Known Member
Forgive my naivete but could you just pour a bottle & do hydro reading from that to get new FG?

#### slowbie

##### Well-Known Member
Forgive my naivete but could you just pour a bottle & do hydro reading from that to get new FG?

You could but it wouldn't help you because the formula for calculating ABV from FG and OG is based on sugar being converted to alcohol and CO2 and would not account for the removal of sugars that took place when the frozen portion was removed.

Also, to the OP, what you really want are chemists, not math people. Math people tend to just make assumptions until they get an answer.

#### Mutant

##### Drinking problem: Can make more than I can drink
Couldn't you take an accurate sample size in ml and heat it to 173.1F to evaporate off the ethanol?

#### ScrewyBrewer

##### ezRecipe - The Easy Way To Awesome Beer!
When beer freezes, sugars and alcohol, will remain in the beer. Adding the weight of sugar and alcohol remaining in the beer will help get you the answer if you also know the weight of sugars retained.

Last edited:

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
Yeah, that's what I figured. In a perfect world, it would be 9%, but then the gravity of my left over gallon should be 1.000.

Oh well, either way I'm sure it'll be delicious.

Thanks for the help.
No. The frozen portion contains some of the proteins, unfermented carbohydrates (dextrins, etc.), and other non-water, non-alcohol components of the beer, which will raise the SG. About the only thing you can assume is that none of the alcohol froze, so it all remains in the recovered liquid. In this case @Killinger 's analysis is the correct one to use.

Brew on

#### ScrewyBrewer

##### ezRecipe - The Easy Way To Awesome Beer!
No. The frozen portion contains some of the proteins, unfermented carbohydrates (dextrins, etc.), and other non-water, non-alcohol components of the beer, which will raise the SG. About the only thing you can assume is that none of the alcohol froze, so it all remains in the recovered liquid. In this case @Killinger 's analysis is the correct one to use.

Brew on
Thank you for clearing this up.

#### doug293cz

##### BIABer, Beer Math Nerd, ePanel Designer, Pilot
Staff member
Mod
No. The frozen portion contains some of the proteins, unfermented carbohydrates (dextrins, etc.), and other non-water, non-alcohol components of the beer, which will raise the SG. About the only thing you can assume is that none of the alcohol froze, so it all remains in the recovered liquid. In this case @Killinger 's analysis is the correct one to use.

Brew on
Looked up the solid/liquid phase diagram for water and ethanol. If you know how to read phase diagrams, and assuming this one is correct, this one tells you that no alcohol freezes out until the temp gets down to about -110°C (166°F.)

Brew on

#### tracer bullet

##### Supporting Member
HBT Supporter
I'd have said something about resurrecting a 12 year old thread, but - seems folks are enjoying it!

#### Big_D

##### Master Of My Domain
HBT Supporter
There are three kinds of people in this world… the ones that are good at math, and the ones that aren’t!

#### SFC Rudy

##### Supporting Member
HBT Supporter
There are three kinds of people in this world… the ones that are good at math, and the ones that aren’t!

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