ABV puzzle

[bobtheUKbrewer2]

my previous brew was OG 1.044 FG 1.016 my spreadsheet calculated strength at 4.16 ABV

the brew I bottled today was OG 1.045 FG 1.009 spreadsheet = 3.82 ABV

this can't be right?????

both beers are MO pale malt and single hop

 

[Yooper]

The formula is (OG-FG) x 131= % ABV.

So, for the first one I come up with 3.67%, and for the second I get 4.71% ABV.

 

[501irishred]

I'm coming up with 3.72%, and 4.78% respectively using a free app on my phone (take it for what its worth). Either way, your second beer IS a higher % than the first.

 

[501irishred]

Sorry Yooper, slow connection today.......

 

[bobtheUKbrewer2]

thanks friends - I actually use a refractometer so I propose to convert to SG and add .004 to the final SG before multiplying by 131

 

[bobtheUKbrewer2]

Does every body agree 5 brix = SG 1.0197

I never get a finishing brix below 5 ????

 

[bobtheUKbrewer2]

OG 11 brix FG 5 brix

if 5 brix were the OG we would get SG1
but 5 brix is the FG of a 4% ABV beer so the 4% alcohol MUST be altering the refractometer reading so 5 brix FG = SG2

is it too low, and by how much?

 

[Yooper]

thanks friends - I actually use a refractometer so I propose to convert to SG and add .004 to the final SG before multiplying by 131

But the brix doesn't "convert" to SG linearly always, and when alcohol is in the mix it's never right. That's probably the whole issue with your spreadsheet.

 

[November]

But the brix doesn't "convert" to SG linearly always, and when alcohol is in the mix it's never right. That's probably the whole issue with your spreadsheet.

And to add even more fun to all that, there seems to be some disagreement as to the exact relationship. My triple scale hydrometer, dual scale refrectometer, and a conversion chart from a brewing manual all agree the 5Brix is 1.020 but when you compare 20Brix the answers are 1.082, 1.078, and 1.086 respectively. I've noticed similar discrepancies in various programs as well.

 

[bobtheUKbrewer2]

1 litre of 4% ABV beer contains 40 ml of alcohol, so there is 960 ml of water and maltose mix, let us say the final SG FROM THE WATER / MALTOSE is 1.015, and let us assume that 4% alcohol 96% water mix is 0.996 SG (somebody on here will supply correct figure), so we have 960 x 1.015 plus 40 x .996 all divided by 1000 which is 1.0142 - so we need to add .0008 to the measured final SG - this is .079% for this 4 % beer - .0008 - so true final SG = 1.0158 - we are talking apparent 3.28 ABV is really 3.17 - anybody still with me?