Alcohol Content

[Suds_Moustache]

I threw out the instructions on how to work out alc/vol of your home brew and so was looking around the internet for the formula.


The first calculation I found is as follows:

1.05 x {(OG - FG)/FG}/ 0.79

Another one is:

(OG - FG) / 7.67

With an OG of 1.040 and a FG of 1.004
the first equation gives you 0.050 (which I rounded off to 5%)

The second gives you 4.95%

I found this handy calculator:
http://www.cascadehomebrew.com.au/brewkits/calculators.asp
Not sure how accurate it is but thought it might be handy for the new-to-brewing types.

The Cascade alc/vol calc (linked above) gives 5.5%

So which one's correct?

Also, anyone used anything like this?
http://www.zdnet.com.au/downloads/0,139024...6986142s,00.htm
I haven't but was wondering how accurate it might be?

 

[ianh]

Dup post

 

[ianh]

Hi

I cannot find the link, but the UK government charged excise as follows

Alc% = (OG - FG) * F

OG - FG F
<0.026 128
.026-.036 129
.036-.046 130
.046-.057 131
.057-.068 132
.057-.068 133
>.068 134

cheers

Ian

 

[Adamt]

When homebrewing, what's more important is the accuracy of the data, rather than the formula.

Either of those formulae work, but will give different numbers due to rounding/truncation of correlation coefficients.

However, how accurate is your data (OG and FG)? Is your hydrometer properly calibrated? Is the sample clear of suspended matter? Did you read the hydrometer correctly?

For an OG of 1.040 and an FG of 1.004, ABV is AROUND 5%, probably +/- 0.5%.

 

[ianh]

Hi Adamt

As you say the readings are probably more important than the formulas. The formulas given are how the UK gov charge excise on micro breweries.

Given standard home brew hydrometers, you would be lucky to read the SG to 0.001. So the formulas are largely irrelevant just use a factor of 131 to covers most things.

Ah when I was at work we use to have hydrometers range 1.000 to 1.050 that measured to 0.0005 should have aquired one.

cheers

Ian

 

[buttersd70]

Hi Adamt

As you say the readings are probably more important than the formulas. The formulas given are how the UK gov charge excise on micro breweries.

Given standard home brew hydrometers, you would be lucky to read the SG to 0.001. So the formulas are largely irrelevant just use a factor of 131 to covers most things.

Ah when I was at work we use to have hydrometers range 1.000 to 1.050 that measured to 0.0005 should have aquired one.

cheers

Ian

Thats how I do it....tallies up with what beersmith says, as well.

 

[Adamt]

Ah when I was at work we use to have hydrometers range 1.000 to 1.050 that measured to 0.0005 should have aquired one.

I wouldn't have bothered! You'd still have the same issues with using the instrument (parallax errors, suspended particles, calibration).

The primary use of the hydrometer for a homebrewer is to determine if fermentation is over - by a stable reading over a couple of days and by being close to the estimated FG - minute accuracy is not necessary or possible.

 

[mouapp12]

Also, anyone used anything like this?
http://www.zdnet.com.au/downloads/0,139024...6986142s,00.htm
I haven't but was wondering how accurate it might be?

most people on here use a program especially for ag though i hadn't heard of that one

i tried to use beersmith once when i was doing extract but got some weird numbers out of it and just started using this which is accurate, though that dosent do bitterness

a thread on diffrent programs if your interested

 

[buttersd70]

my old nemesis, the brewcraft calculator.....the maths don't add up.

for example, 3kg LME:

SG= hwe x EE x wt /V

SG 310x1x3/20 = 46.5, ie 1.0465. Brewcraft gives 1051.

eg2: 3kg dextrose, 20L.....brewcraft says 1.061

386x1x3/20= 57.9 ie 1.058.......to get 1061, the potential of dex would have to be 406.6HWE....which is 105.354%.

 

[jonocarroll]

1.05 x {(OG - FG)/FG}/ 0.79

Another one is:

(OG - FG) / 7.67

Linky - Just in case you want to know where they come from.