View Full Version : Calculating ABV after dilution and with one unknown factor.

12-01-2015, 08:07 PM
So I have a batch which, after a few times racking shrunk in volume from 15 liters exactly to an unknown size <15 liters. The starting gravity was 1.130 and the final gravity of this batch of <15 liters is 1.020. That's 14,44% alcohol before adding the following:

I've added a total of 1650ml which does not contain any alcohol and has not fermented, it's pure dilute. After adding this to the batch, what is the new alcohol contents?

Original Volume: 15 liters
Current Volume: ?
Original Gravity: 1.130
Current Gravity: 1.026
Current Alcohol: 13,65%

Addition: 1650 ml
New Alcohol: ?

Sounds like a question from a math book and I really really suck at maths. :( Please halp!

12-01-2015, 09:02 PM
Without knowing the volume before or after you diluted the batch, there is now way to figure out the alcohol content mathematically.

12-02-2015, 01:35 PM
Does the new addition contain sugar? Is it juice or honey & water or something? If it's just water, you can work it out based on the new SG. If you've also added sugar, that option is also out.

12-03-2015, 10:42 AM
It's just water, nothing fermentable, and purely 1.000 gravity.

12-03-2015, 02:06 PM
Okay, so you should be able to take your new SG and work it out.

Take your old FG (1.026) and put that into the mead calculator as the starting SG. Then put your new FG in as the FG. This will give you the ABV drop.

So it you went from 1.026 to 1.010, that gives about a 2% drop, which would make your batch now about 11.65%