Hydrometer readings and ABV

[Jonathan Barnes]

Sorry for what I'm sure is a very basic and regularly asked question!

I cannot for the life of me get the various calculations I have found to work out alcohol content from a hydrometer reading to come up with a recognisable number. Does anyone have a simple way to explain??

If I read the hydrometer right, the OG was 1.0325 (ie one line underneath 30), and the FG 1.0125 (ie one line under 10).

Also, I took the reading from the liquid being transfered from the fermenting bucket into bottles, but another spoon of sugar went into the bottles which didn't go into the sample... Would this need to be factored?

Thanks in advance!

 

[Dutto]

Starting from basics:

1. Most (but not all) hydrometers give a Specific Gravity (SG) that is accurate when:
   • The liquid is at 20*C.
   • The liquid is measured from the bottom of the meniscus. (i.e. the flat bit surrounding the hydrometer and not the bit the climbs up the side of the hydrometer.)
2. The Original Gravity (OG) of the wort is the gravity measured before the addition of any yeast or yeast nutrients.
3. The Final Gravity (FG) of the brew is the gravity measured after fermentation has ceased but before bottling.
4. The OG and the FG are used to give the Alcohol By Volume (ABV) of the brew. (*) (The SG falls as the sugar is consumed and turned into a mixture of CO2 and alcohol.)
5. After taking the FG sugar is (**) introduced to allow carbonation to take place. This is called Priming Sugar.
6. It is traditional to add 0.5% to the ABV figure to account for the addition of the Priming Sugar before bottling.

I hope this makes sense.

(*)
It is too early to go into the mathematics of the actual Formula used for this calculation; which is why an ABV Calculator is contained in the "Calculators" section at the top of this page.

(**)
Carbonating sugar isn't required when a brew is carbonated using CO2 gas.

PS

From the figures you have given (OG 1.0325 and FG 1.0125) the ABV is at 2.63%.

Normally I expect an FG of about 1.010 which would give an ABV of 2.95%. This is still a bit low for an ABV but maybe you planned it that way.

Maybe the brew hasn't finished fermenting.

 

[xozzx]

OG seems very low unless you were going for low ABV beer.
Most standard hydrometers will only read to 3 decimal places, not sure where the final 5 is coming from. Assuming 5 lines between each marked scale (1.020, 1.030, etc) then one line below 1.030 would be 1.032. Doesnt make a big difference but good to get it right.

Brewers friend has a good calculator https://www.brewersfriend.com/abv-calculator/

 

[terrym]

First to make sure you are reading your hydrometer correctly try this
https://www.thehomebrewforum.co.uk/...ty-using-a-homebrew-hydrometer.60895/readings (
Then if you have the OG and the FG (latter before you add the priming sugar) try this to correct for temperature relative to your hydrometer calibration temperature (which will be marked somewhere on the hydrometer, usually its 20*C).
https://www.brewersfriend.com/hydrometer-temp/
If the beer temperature is near room temperature it will make little real difference.
Next using the corrected OG and FG values use this to calculate the ABV before priming
https://www.brewersfriend.com/abv-calculator/
Finally the priming sugar will add about 0.5% alcohol.
Job done