The Gravity of It All....

[jazzmini1959]

Can anyone tell me how to work out the gravity of homebrew ? Mine started at 103 and is now 102 after a week - any idea what the gravity would be ?

Cheers m'dears

Rob Wiltsher
Bishopston, Bristol

[boboff]

To calculate Alcohol by Volume: Subtract the last reading from the initial gravity and divide the result by 0.0074. This gives the approximate alcohol content in %. Ex.: S.G. = 1.070 F.G. = 0.995 1.070 - 0.995 = 0.075 0.075 / 0.0074 = 10.15% It does not matter what the first or last reading is, both mean little alone. The difference between the two does! Usually there is also an alcohol scale marked directly on a hydrometer; subtract initial potential alcohol reading from final, and the difference is the approximate alcohol content. Using the Brix scale, 1 degree Bx = 1 g/100 ml, or 10 g/liter. When you read a Bx of say 22, divide the 22 by 2 to get 11, and add 1, for a final alcohol of 12%. It is an extremely good rule of thumb.

[jazzmini1959]

Thanks for that, Boboff ! My initial gravity was 1.35 and the latest was 1.20. Subtract one from the other and I get 0.15. Divide that by .0074 and I get 20.2 % !! Is that right ?

[Green Aura]

My hydrometer has a yellow band that says "bottle" - we go off that!

[boboff]

Hi Jazz.
I would check your readings, and I wouldn't bottle until you are sure no more fermentation.
Be 100% sure you are recording accurately, but I wouldn't worry, taste it?

[MKG]

Hydrometers are great - but be careful. If there are lots of solids held in the liquid (like when you start a wine off) then the hydrometer will float higher, giving you a false reading. Similarly, if you're testing a wine or beer which is still fermenting, bubbles of carbon dioxide can stick to the hydrometer, once more making it float high and giving a false reading.

I only use my hydrometer these days to give me an approximate guide when I'm feeding a wine. Otherwise I use the E/NE alcohol scale (Enough/Not Enough) and the "Oh, there's no more bubbles and it's clear" method of judging the stage of a fermentation.

Mike

[jazzmini1959]

Thanks for all your help, guys. I normally just give the hydrometer a bit of a spin between my fingers to get rid of the bubbles attached to it. I bottled it last night as it looked good so will find out what it is like in 10 days or so......