Calculate Gravity Post Boil? - Home Brew Forums

 Home Brew Forums > Calculate Gravity Post Boil?

11-23-2009, 02:24 AM   #1
JMSetzler

Recipes

Dec 2008
Hickory, North Carolina
Posts: 901
Liked 15 Times on 15 Posts

I ran into a problem somewhere in my gravity readings during my brew today. I took a pre-boil gravity reading of 1.036 which was right on target what what I expected it to be. The pre-boil volume was 6.75 gallons. My post boil gravity reading was 1.037, which simply can't be correct with a volume of 5.5 gallons. I was expecting a post boil gravity of approximately 1.043. I took these gravity readings with a refractometer (Brix) and made the conversions (double checked).

How can I calculate my post boil gravity mathematically based on my pre-boil gravity and the two volumes?
__________________
Beer Before Noon - My Beer and Homebrewing Adventures

Kamado Joe Cooking Channel - Grillin' up a Storm!

11-23-2009, 02:28 AM   #2
Doc Robinson

Recipes

Oct 2009
Bonita Springs, Florida
Posts: 2,354
Liked 20 Times on 16 Posts

I believe it is 36 x (6.75/5.5) = 44 or 1.044.

11-23-2009, 02:34 AM   #3
JMSetzler

Recipes

Dec 2008
Hickory, North Carolina
Posts: 901
Liked 15 Times on 15 Posts

I came to that conclusion too.. thanks for the input. I was tryint to calculate using 1.036 instead of just using 36...
__________________
Beer Before Noon - My Beer and Homebrewing Adventures

Kamado Joe Cooking Channel - Grillin' up a Storm!

11-23-2009, 12:35 PM   #4
Doc Robinson

Recipes

Oct 2009
Bonita Springs, Florida
Posts: 2,354
Liked 20 Times on 16 Posts

Quote:
 Originally Posted by JMSetzler I came to that conclusion too.. thanks for the input. I was tryint to calculate using 1.036 instead of just using 36...
[1,000 x (PreBG - 1)] x [PreBV/PostBV] = (PostBG/1000) +1