% ABV

[Tom Wrinkles]

What is the most accurate and/or easiest way to calculate alcohol by volume?

[Don]

If you want to keep your math skills active you can try this way:
There are a number of formulas, but for all practical purposes you can get a simple answer that is close enough by using this one;

Original gravity minus Final Gravity times 129=your approximate homebrew alcohol by volume (ABV).

For example, a homebrew with an original gravity of 1.050 and a final gravity of 1.015 would be calculated as follows: 1.050-1.015=0.035X129=4.51% ABV
or
Take the SG reading at the time you pitch the yeast in the wort. Call that A.
Take the SG reading when fermentation is completely finished. Call that B.
Subtract B from A. Call the answer C.
Multiply C by 1.05 and call the answer D.
Divide D by B and call the answer E.
Divide E by 0.79 and the answer is the percentage of alcohol (by volume).

Here's how it works:
Assume the original gravity was 1.048 (standard for most commercial wort), and the final gravity was 1.012 (a typical value).
1.048 minus 1.012 equals 0.036 (there's our C).
0.036 times 1.05 equals 0.0378 (that's D).
0.0378 divided by 1.012 equals 0.03735 (roughly), which is E.
0.03735 divided by 0.79 equals 0.04728 or a little over 4.75% alcohol.
or
There are an endless number of web sites and all your beer programs will do the math for you.
Just get the starting and ending SG and plug then in
or
I can't find the numbers right now, but you can also weigh your carboy before and after it done fermenting to figure out the ABV.

[Tom Wrinkles]

If you want to keep your math skills active you can try this way:
There are a number of formulas, but for all practical purposes you can get a simple answer that is close enough by using this one;

Original gravity minus Final Gravity times 129=your approximate homebrew alcohol by volume (ABV).

For example, a homebrew with an original gravity of 1.050 and a final gravity of 1.015 would be calculated as follows: 1.050-1.015=0.035X129=4.51% ABV
or
Take the SG reading at the time you pitch the yeast in the wort. Call that A.
Take the SG reading when fermentation is completely finished. Call that B.
Subtract B from A. Call the answer C.
Multiply C by 1.05 and call the answer D.
Divide D by B and call the answer E.
Divide E by 0.79 and the answer is the percentage of alcohol (by volume).

Here's how it works:
Assume the original gravity was 1.048 (standard for most commercial wort), and the final gravity was 1.012 (a typical value).
1.048 minus 1.012 equals 0.036 (there's our C).
0.036 times 1.05 equals 0.0378 (that's D).
0.0378 divided by 1.012 equals 0.03735 (roughly), which is E.
0.03735 divided by 0.79 equals 0.04728 or a little over 4.75% alcohol.
or
There are an endless number of web sites and all your beer programs will do the math for you.
Just get the starting and ending SG and plug then in
or
I can't find the numbers right now, but you can also weigh your carboy before and after it done fermenting to figure out the ABV.

Thanks Don. I have been using this one.
OG=1.050
FG=1.012
1.050-1.012= 1.038
38/7.4=5.14%

[Don]

Thanks Don. I have been using this one.
OG=1.050
FG=1.012
1.050-1.012= 1.038
38/7.4=5.14%

Should be @4.95% not too far off

[Ritchie]

I just what to know how you did your math.

1.050
-1.012
--------
1.038

how about doing it with out the place value in font of the decimal place ((1))

Ritchie

[Don]

I just what to know how you did your math.

1.050
-1.012
--------
1.038

how about doing it with out the place value in font of the decimal place ((1))

Ritchie

1.050
-1.012
--------
0.038
* 129
=4.902 %
========

.050
-.012
.038
* 129
=4.902

[Tom Wrinkles]

I just what to know how you did your math.

1.050
-1.012
--------
1.038

how about doing it with out the place value in font of the decimal place ((1))

Ritchie

Here is a link where I got this formula.
http://www.hambletonbard.com/how-to-mak ... shine.html

[ArtCox]

What is the most accurate and/or easiest way to calculate alcohol by volume?

OG - FG X 129 = ABV