I have a big beer in primary at the moment and I'm contemplating the calculations for ABV. I had a rather large starter, so I want to get a sense of how much I should adjust for the dilution from that starter. The starter brings gravity and alcohol to the batch, so it's not like dilution with water.
Is this method and math sound?
I assume that I should adjust my OG for the gravity points contributed from the starter. FG of the entire batch from that adjusted OG should give me an accurate ABV. Correct?
OG before starter = 1.121
Volume before starter = 4.6 gal
Starter OG = 1.037
Starter Volume = 0.375 gal (does not include volume of slurry)
So....
(1.121 - 1) * 1000 * 4.6 = 556.6 gravity points*gallon from wort
(1.037 - 1) * 1000 * 0.375 = 13.9 gravity points*gallon from starter
556.6 + 13.9 = 570.5 total gravity points*gallon
4.6 + 0.375 = total gallons of volume
1 + ((570.5/4.975) / 1000) = 1.115 adjusted OG
If my FG = 1.025, than I calculate...
11.75% AVB from adjusted OG, as opposed to
12.6% ABV without adjusting for the starter.
Is this an accurate way to adjust ABV for a big starter?
Is this method and math sound?
I assume that I should adjust my OG for the gravity points contributed from the starter. FG of the entire batch from that adjusted OG should give me an accurate ABV. Correct?
OG before starter = 1.121
Volume before starter = 4.6 gal
Starter OG = 1.037
Starter Volume = 0.375 gal (does not include volume of slurry)
So....
(1.121 - 1) * 1000 * 4.6 = 556.6 gravity points*gallon from wort
(1.037 - 1) * 1000 * 0.375 = 13.9 gravity points*gallon from starter
556.6 + 13.9 = 570.5 total gravity points*gallon
4.6 + 0.375 = total gallons of volume
1 + ((570.5/4.975) / 1000) = 1.115 adjusted OG
If my FG = 1.025, than I calculate...
11.75% AVB from adjusted OG, as opposed to
12.6% ABV without adjusting for the starter.
Is this an accurate way to adjust ABV for a big starter?