# How to compute alcohol content

### Help Support Homebrew Talk:

#### ian

##### Well-Known Member
I've been reading on this and I can't find a difinitive formula to compute alcoholic content. Its not a big deal. I'm not trying to brew a high alcohol content beer, I was just curious.

I've got a hydrometer and plan to use it this weekend on my first brew but I don't really know how to use it to determine alcohol content.

Thanks,
Ian

##### Well-Known Member
Abw = 76.08(og-fg)/(1.775-og)

Abv = Abw (fg/.794).

#### rsitzejr

##### Well-Known Member
Abw = 76.08(og-fg)/(1.775-og)

Abv = Abw (fg/.794).
I'm pretty lousy at math, so can someone explain this one better?

#### bikebryan

##### Well-Known Member
rsitzejr said:
I'm pretty lousy at math, so can someone explain this one better?
Just get a copy of ProMash. You can get an eval copy for free. It has a % acohol computer built into it. You just plug in your OG and FG and it does the rest.

#### cygnus128

##### Well-Known Member
rsitzejr said:
I'm pretty lousy at math, so can someone explain this one better?
Are you looking for a why? The formula looks complicated but it is really just plugging your og and fg numbers in and then calculators away!

##### Well-Known Member
The way I've been doing ABV is OG-FG*105

Example: My Scottish Ale--1.085-1.015=.07
.07*105=7.35ABV

I can't remember exactly where I got this but it has seemed pretty accurate.

#### rsitzejr

##### Well-Known Member
The way I've been doing ABV is OG-FG*105

Example: My Scottish Ale--1.085-1.015=.07
.07*105=7.35ABV

I can't remember exactly where I got this but it has seemed pretty accurate.
Now that sounds like what's in "The Joy's of Homebrewing" book.

OP

#### ian

##### Well-Known Member
Abw = 76.08(og-fg)/(1.775-og)

Abv = Abw (fg/.794).
Ok, please excuse my ignorance but what does Abv stand for?
Also Abw, what does that stand for.

I'm assuming it means Alcohol By Volume or Alcohol By Weight. But, I'm guessing.

#### kenmc

##### Well-Known Member
ian, thats spot on...

OP

#### ian

##### Well-Known Member
Thanks Ken,

I'm brewing on Saturday and I can't wait. It can't come soon enough, for me or my wife. She's getting tired of me talking about it!

I'm going with a Belgian White kit that I ordered from a homebrew supply store about 2 hrs from where I live. It'll be here probably today!

I chose the Belgian White as it seems that you can ferment at higher temps without worrying. I live in South Carolina, and to cool our house to a normal fermenting temp would get rather expensive.

OP

#### ian

##### Well-Known Member
OK I tried using both of the formulas that you guys have given.

OG=1.04
FG=1.01

Brewhead's formula produces ABV of 3.95%
And AlaskaAl(e)'s produces ABV of 3.15%

Although, there could be an error on my part for computation. But, that seems to be a fairly big discrepancy.

What do you guys think. By the way, this is purely academic as I don't really care if my beer is super alcoholic. I mean, I want it to be somewhat alcoholic . . .

#### bikebryan

##### Well-Known Member
ian said:
OK I tried using both of the formulas that you guys have given.

OG=1.04
FG=1.01

Brewhead's formula produces ABV of 3.95%
And AlaskaAl(e)'s produces ABV of 3.15%

Although, there could be an error on my part for computation. But, that seems to be a fairly big discrepancy.

What do you guys think. By the way, this is purely academic as I don't really care if my beer is super alcoholic. I mean, I want it to be somewhat alcoholic . . .
Assuming you actually meant a OG of 1.040 and a FG of 1.010, ProMash figures this at 3.94% ABV. I'd go with Brewhead.

##### Well-Known Member
ian said:
Ok, please excuse my ignorance but what does Abv stand for?
Also Abw, what does that stand for.

I'm assuming it means Alcohol By Volume or Alcohol By Weight. But, I'm guessing.

http://www.beerchurch.com/gloss.htm

##### Well-Known Member
But, that seems to be a fairly big discrepancy
i bet you're brain or liver will never know

OP