# Equation for alcohol content



## PeterZ (Nov 28, 2006)

ISTR seeing an equation about initial SG - final SG x some factor = alcohol. Does anybody have this equation?


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## Waldo (Nov 28, 2006)

Starting SG minus Ending SG Multiplied by 131 will give you ABV
1.090 - .990 = .01 x 131 = 13.1%


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## CajunTim (Nov 28, 2006)

What does the 131 represent? Is that for all batch sizes?


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## Wade E (Nov 28, 2006)

Yes, and I dont know. This is the way I was taught, Take your initial
SG not usiing decimals 1090, subtract your finished SG 990=100, and
then divide by 7.36. Your alc % =13.58. Which is actually the true way
please.


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## NorthernWinos (Nov 28, 2006)

wadewade said:


> Yes, and I dont know. This is the way I was taught, Take your initial
> SG not usiing decimals 1090, subtract your finished SG 990=100, and
> then divide by 7.36. Your alc % =13.58. Which is actually the true way
> please.



This is the way I had read to do it too....


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## Wade E (Nov 28, 2006)

At least I'm not alone then. Thank you. I figured I was going to be the only loser with the wrong formula.


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## Waldo (Nov 29, 2006)

CajunTim said:


> What does the 131 represent? Is that for all batch sizes?




Don't have a clue as to what it represents Cajun but it is the formula for whatever size batch you are making.


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## Waldo (Nov 29, 2006)

As with all aspects of wine making..there are numerous ways of doing the same task ..All are right and none are wrong. A matter of personal preference. In this case, I can multiply quicker than I can divide


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## Wade E (Nov 29, 2006)

I dont know about that Waldo. You seem to be able to divide a bottle of wine into one glass very quick.


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## kutya (Nov 29, 2006)

Wade, I measure mine the same way. You are not the only loser with the wrong calculations....


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## peterCooper (Nov 29, 2006)

http://www.ritchieproducts.co.uk/calculatingABV.htm

From which I gather that....

17 grams of sugar per liter per 1% ABV. 5083 grams to produce 13% in a 6 gallon batch. However, different yeast strains vary from that rough figure because the different strains produce other volatiles in varying quantities so the calculatio. can be + or - .3% ABV depending on the yeast strain.


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## CajunTim (Nov 29, 2006)

_This is the one I used. It came off a sitefrom roger.simmondsfor homemade wine making for beginners._





Firstly find the degrees of gravity lost by deducting the final s.g from the initial s.g. Ignore the decimal point. 


Next you will need to select a factor from the table below. The factor is determined by the original s.g. 
<CENTER>
<TABLE cellSpacing=20>
<T>
<TR>
<TD>
<TABLE border=1>
<T>
<TR align=middle>
<TH>Original s.g.</TH>
<TH>Factor 
<TR align=middle>
<TD>1.160</TD>
<TD>6.82 
<TR align=middle>
<TD>1.150</TD>
<TD>6.84 
<TR align=middle>
<TD>1.140</TD>
<TD>6.87 
<TR align=middle>
<TD>1.130</TD>
<TD>6.90 
<TR align=middle>
<TD>1.120</TD>
<TD>6.93 
<TR align=middle>
<TD>1.110</TD>
<TD>6.96 
<TR align=middle>
<TD>1.100</TD>
<TD>7.00 
<TR align=middle>
<TD>1.090</TD>
<TD>7.04 </TD></TR></T></TABLE>
<TD>
<TABLE border=1>
<T>
<TR align=middle>
<TH>Original s.g.</TH>
<TH>Factor 
<TR align=middle>
<TD>1.080</TD>
<TD>7.09 
<TR align=middle>
<TD>1.070</TD>
<TD>7.14 
<TR align=middle>
<TD>1.060</TD>
<TD>7.20 
<TR align=middle>
<TD>1.050</TD>
<TD>7.29 
<TR align=middle>
<TD>1.040</TD>
<TD>7.39 
<TR align=middle>
<TD>1.030</TD>
<TD>7.45 
<TR align=middle>
<TD>1.020</TD>
<TD>7.52 
<TR align=middle>
<TD>1.010</TD>
<TD>7.59 </TD></TR></T></TABLE></TD></TR></T></TABLE></CENTER>Finally you need to devide the degrees of gravity lost by the factor to find the percentage of alcohol by volume. 


As an example; original s.g is 1.110, final s.g. is 1.004
Degrees lost (ignoring decimal) = 1110 - 1004 = 106
Percentage alcohol by volume = 106/6.96 = 15.23%


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## Coaster (Nov 29, 2006)

AHHHHHHHHHHHHHHHH!!


three different methods, three different results


S SG 1.090
E SG 0.990


Method 1 1090 - 990 = 100
100 / 7.36 = 13.6%


Method 2 1.090 - .990 = .1
.1 * 131 = 13.1%


Method 3 1090 - 990 = 100
100 / 7.04 = 14.2%


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## NorthernWinos (Nov 29, 2006)

Coaster said:


> AHHHHHHHHHHHHHHHH!!
> 
> three different methods, three different results
> 
> ...



Now I am really confused


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## CajunTim (Nov 29, 2006)

Now I am really confused



[/QUOTE] 



That makes two of us.



I wonder which one is closest to an alcohol tester?


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## peterCooper (Nov 29, 2006)

get a gas spectrometer (anything from $2,000 - $20,000 and you should be able to get accurately enough (of course you need the Ph.D. as well)


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## Wade E (Nov 29, 2006)

I'll go get both tommorow!


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## AAASTINKIE (Nov 29, 2006)

1.090-.990 X 1000 X .129 = 12.9
no wonder my wines are weak, I'm using the wrong formula..lol


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## Wade E (Nov 29, 2006)

Oh no, not another formula!


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## Joseph1 (Nov 29, 2006)

If you want to know the exact alcohol content of your wine you will need to spend a few hundred dollars and purchase an Ebulliometer. If you are not a commercial winery, exact is not necessary. To obtain a ballpark idea of alcohol content, any of the many formulas or tables available to home winemakers will do.<?amespace prefix = o ns = "urnchemas-microsoft-comfficeffice" />

For those interested in yet another formula for calculating potential alcohol, I present the following for your entertainment and amusement. The formula is based on the work of Bryan Acton and Peter Duncan and is from their book <I style="mso-bidi-font-style: normal">Progressive Winemaking[/I]. This is the only formula I am aware of that makes the claim of being within plus or minus 0.5% of an Ebulliometer. This claim is for wines with an alcohol content of 10% to 14%.

ABV (Alcohol by Volume) = (OG – FG) / (7.75 – (3 * ((OG – FG – AG) / 800)))

Where:
OG = Original Specific Gravity times 1000 (i.e. 1.100 * 1000 = 1100)
FG = Final Specific Gravity times 1000
AG = Gravity adjustment. This is an adjustment to correct for the non-sugar solutes in the juice or wine. The authors state that the correction is usually between specific gravity 0.005 and 0.010. They recommend using 0.007. This number is also multiplied by 1000.

Example:

OG = 1100 (Original Specific Gravity of 1.100 * 1000)
FG = 1000 (Final Specific Gravity of 1.000 * 1000)
AG = 7 (the recommended 0.007 * 1000)

PA = (1100 – 1000) / (7.75 – (3 * ((1100 – 1000 -7) / 800)))
= (100) / (7.75 – (3* (93 / 800)))
= 100 / (7.75 – (3 * 0.116))
= 100 / (7.75 – 0.349)
= 100 / 7.40
= 13.51% ABV

If you repeat the above calculation with a final gravity of 0.990, the result will be 110 / 7.36 (Wade, does this denominator look familiar?) or 14.9% ABV.

I hope I got it right. Have fun!


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## Coaster (Nov 29, 2006)

To me, it appears that the divide by 7.36 is the fastest and closest. Over several ranges it is 0%to 0.2%higher thanthe formula that Joseph posted (and that is within +/- 0.5%). Therefore I thinkI shall add ~ in front of all my %'s. 8O)


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## sangwitch (Nov 30, 2006)

here's what I get on my ice wine. (1.150; 1.052)


#1 (waldo) 12.8
#2 (wade) 13.3
#3 (cajun) 14.3
#4 (stinkie) 12.6
#5 (joseph) 13.2

 
Has anyone charted their favorite formula on a spread sheet? That way all you would need to know is the difference between original and ending SG and then look at the chart.


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## Wade E (Nov 30, 2006)

Step right up and guess your alc.


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## kutya (Dec 2, 2006)

Here is another one I found on the net.


SG start - SG finish divided by 10 X1.3 


1.150-1.052=.098 divide by 10=.0098 x 1.3= 12.7%


Anyone confused yet?????


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## Waldo (Dec 3, 2006)




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