Figuring Out The Abv Of My Homebrew?

[casualties_army40]

hey im just wondering on figuring out how much alcohol is in my homebrew?

i tried to make it with more alcohol in it so i added more sugar to it half way through fermentation. i know how to calculate the abv with a hydrometer using the OG and FG but i have a question.

if lets say i have a OG of 1.042 then i pitch the yeast and let it do its thing for a fewdays and i check the SG and its at, lets say,1.020 or something then i add morw sugar to it. i let it ferment and when it does i take the FG before bottling. now to figure out how much alcohol is in it i couldn't use the OG and FG method (or could i?) because the SG would have changed when i added sugar!? so how do i go about calculating the ABV? instead of using the OG do i take another SG reading after i add more sugar and use that in the 'determining alcohol content' formula? or!???

so the question in a more simple way, how do i calculate the ABV if the SG has been changed half way through fermentation by adding more sugar to increase the ABV?

id really appreciate any help people have got to offer. cheers and beers.

 

[manticle]

If you use a spreadsheet like this one: http://hbd.org/cgi-bin/recipator/recipator and enter all your data (including extra fermentables) it will give you a rough idea.

 

[bradmcm]

Sugar has a Hot Water Extract of 386 litre degrees per kilogram.
Which means that 1kg of sugar will contribute 386 hydrometer points per litre.
So multiply the amount of sugar in kilograms by 386 and divide it by the size of your brew and thats how many points were added to your starting gravity.

 

[glaab]

The easy way out is if your second sugar addition raises from 1020 to 1030 just add 10 points to your OG and it oughta be close enough.

 

[casualties_army40]

So multiply the amount of sugar in kilograms by 386 and divide it by the size of your brew and thats how many points were added to your starting gravity.

is it multiply the amount of sugar 'added' or multiply the amount of sugar altogether that was put in through out the brew?

but thanks heaps.

 

[Ester Trub]

A really easy, but probably not extremely accurate beer calculator can be found here:
http://www.brewcraft.com.au/wa.asp?idWebPa...p;idDetails=172

Just tell it what you put in, (in kg), including your extra sugar and it'll give you an approximate alcohol content.

 

[boingk]

Amount added. I'll use your SG of 1.042, and say it got down to 1.010. That would normally give me around 4.6% alcohol.

BUT - I added another 200g of sugar along the way. 200g is .2 of a kilo, so .2 multiplied by 386 is 77.2, and 77.2 divided by brew volume of 23 litres gives 3.36. Call it 3. Add that to your SG reading and it'll be 1.045, giving you an alcohol percentage of about 4.9.

See? Easy.

Cheers - boingk