  1. Calculation Formulae (SG, %ABV,...)

From somewhere else in the Forum

SPECIFIC GRAVITY from HONEY quantity

SG = 1 + [ (lbs x 45) / (gals x 1000) ]

(and for metric people)

SG = 1 + [ (Kg) / (Ltr x 2.6596) ]

POTENTIAL ALCOHOL from SG

(This allows for FG < 1.000 - see Ben Rotter's site http://members.tripod.com/~BRotter/C...o/HydSugAl.htm )

%ABV = 0.944 + 129.8 x (SG - 1)

Any other handy formulae out there?  Reply With Quote

2. Piping Queen  Join Date
Aug 2004
Posts
600 Re: Calculation Formulae (SG, %ABV,...)

POTENTIAL ALCOHOL from SG

(This allows for FG < 1.000 - see Ben Rotter's site http://members.tripod.com/~BRotter/C...o/HydSugAl.htm )

%ABV = 0.944 + 129.8 x (SG - 1)

Any other handy formulae out there?
Would I be correct in assuming that should be
%ABV = 0.944 + [129.8 x (SG-1)] ?  Reply With Quote

3. Worker Bee  Join Date
Nov 2003
Posts
378 Re: Calculation Formulae (SG, %ABV,...)

My rule of thumb is 1 lb of honey in 5 gals of water = 0.008 SG = 1% ABV fermented out. Simple, pretty close to reality, and much easier to remember than those equations. I have a question about that SG to ABV formula. If I plug in a SG of 1 (= water), I get a ABV% of .994%. What gives?  Reply With Quote

4. Piping Queen  Join Date
Aug 2004
Posts
600 Re: Calculation Formulae (SG, %ABV,...)

My rule of thumb is 1 lb of honey in 5 gals of water = 0.008 SG = 1% ABV fermented out. Simple, pretty close to reality, and much easier to remember than those equations. I have a question about that SG to ABV formula. If I plug in a SG of 1 (= water), I get a ABV% of .994%. What gives?
I guess that's what happens when you use a simplified equation to get an approximation. On the "Mead Made complicated" site they give the actual equations to figure this out, those equations frighten and confuse me   Reply With Quote

5. Re: Calculation Formulae (SG, %ABV,...)

WikdWaze,

The brackets were left out because I assumed muiltiplication has precedence over addition Goes to show what assuming does.

Scott S,

Plugging in SG=1.000 says that your FG=1.000, and your mead isn't totally dry, but still has 0.944% Alc to ferment out.
When your FG=0.9927 you will have a totally dry mead. Again this is another assumption, because EC-1118 can probably ferment to FG=0.9927, but some of the other yeasts may not. However, we are talking about potential alcohol I'm sure you didn't start with OG=1.000 The URL I mentioned has more details, and there are 5 formulae listed there, each with slightly different results.

-=-=-=-

1lb in 5 gal making 1% ABV - that is an easy one to remember, except for the "metric" people :-/

that makes it (roughly) 0.4 Kg in 19 Litres per 1% ABV  Reply With Quote

6. Re: Calculation Formulae (SG, %ABV,...)

Nice references James! Good information!

Oskaar  Reply With Quote

7. jab Piping Queen  Join Date
Mar 2004
Posts
557 Re: Calculation Formulae (SG, %ABV,...)

I started writing a PHP application a while back that would allow me to track my brews. Life got in the way and I didn't get very far on it, however, this is the function I was using to figure alcohol content either by weight or vol.

Code:
```<?

function figureAlcohol(\$ograv, \$fgrav, \$pmode = 'vol')
{
\$alc = ((\$ograv - \$fgrav) * 105);

if (\$pmode == 'vol')
{
\$alc *= 1.25;
}

return \$alc;
}

?>```
Hope that helps someone.

-jb  Reply With Quote Re: Calculation Formulae (SG, %ABV,...)

I developed a little spreadsheet that helps you formulate simple recipes, if anybody's interested. Just PM me with your e-mail and I'll send it to you.

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