Specific Gravity

blueboron · Jun 23, 2011

Reading the forum messages I see references to the starting SG, amounts of sugar and from that a reference to the finished SG and Alcohol Content.

Is there a guide on this forum to read so I can make an attempt to understand just what it is all about :wha:

Just bottled 20 litres of Youngs Buddy White - did not taste too bad so hopefully in about 3 months it will be drinkable I took an SG reading and it was about 0.990 - in the green on the hydrometer - not sure how to work out the Alcohol content from that.

I have since found an ABV Calculator and have put a few different figures in to see what happens - The higher the starting SG and the lower the end SG the more ABV.

Does anyone know the maths involved to make that calculation?

Have not a clue what the starting SG was but I would think that with a kit and following the exact recipe the starting SG would be constant - I suppose an email to Youngs would solve that one.

Just one question - I have made the assumption that the more sugar at the start will increase the SG, how do you know that the yeast will cope with the extra etc

Bye for now

BB

Damsonite · Jun 24, 2011

Is there such a thing as a be-all end-all formula for wine making other than by rule of thumb frequent hydrometer testing? Don't think so as any such calculation assumes fixed controls - i.e. sugar in the gallon/sugar added to the gallon, regardless of the nature of a must and its' constituent ingredients. Problem is that 'across the board' calculations don't allow for fluctuations in a yeasts' ability to split sugar into glucose/fructose in a given volume of must - one gallon might end up entirely different to another seemingly identical gallon, dependent on several variables. None of this is an exact science, and that's half of the fun...

StubbsPKS · Jun 24, 2011

blueboron said:
Reading the forum messages I see references to the starting SG, amounts of sugar and from that a reference to the finished SG and Alcohol Content.

Is there a guide on this forum to read so I can make an attempt to understand just what it is all about :wha:

This (Clicky) might have some of the info you're looking for in it.

blueboron said:
I have since found an ABV Calculator and have put a few different figures in to see what happens - The higher the starting SG and the lower the end SG the more ABV.

There is a calculator link at the top left of the forums. In there is a handy calculator for ABV from OG (original gravity) and FG (final gravity).

blueboron said:
Just one question - I have made the assumption that the more sugar at the start will increase the SG, how do you know that the yeast will cope with the extra etc

If you are using a well-known yeast then you should be able to google the strain to find out how much alcohol it can handle producing.

evanvine · Jun 24, 2011

If you subtract the FG from the OG and divide by 7.36(Moley) or 7.46(me).
I now use 7.41(middle fig)
EG
OG 1.044, FG 1.002
Taking the figs after the point and treating them as whole nos.
44 - 2 = 42
42/7.41 = 5.668
Rounded = 5.7% ABV
An accurate enough fig for our needs!

blueboron · Jun 24, 2011

Thanks for the replies :thumb:

Damsonite · Jun 25, 2011

@evanvine... What does the 7.41 (or 7.36~7.46) represent?

evanvine · Jun 25, 2011

It is a constant, just accept it!

Some use 7.36, others use 7.46, an average of the two = 7.41.
I always used to use 7.46.
If you want higher accuracy, you will need to visit UK customs.

Specific Gravity

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