Author Topic: calculating gravity adjustments during boil  (Read 1470 times)

Offline dzlater

  • Brewer
  • ****
  • Posts: 411
  • Dan S. New Jersey
    • View Profile
calculating gravity adjustments during boil
« on: March 28, 2010, 12:21:34 PM »
I've been  reading Designing Great Beers, and it gives some formulas for hitting
your target OG by either adjusting your final volume or adding extract, or top off water.
I can follow the math in the book but was wondering if there was an on line
calculator type thing or maybe a spreadsheet to make this easier.
Or maybe a website that lays the math out in a way that's easier to use.
Anyone ever use this Beer Recipe Calculator
 http://www.northernbrewer.com/brewing/brewing-books/software/beer-recipe-calculator.html
If it does what I want it to, I might buy it if I can find at one of my local shops.
« Last Edit: March 29, 2010, 03:46:57 AM by dzlater »
Dan S. from NJ

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3568
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: calculating gravity adjustments during boil
« Reply #1 on: March 28, 2010, 09:52:06 PM »
No calculator required IMHO.

G1*V1 = G2*V2

When adding extract, solve for G1. To dilute, solve for V2.
Beer is like porn. You can buy it, but it's more fun to make your own.
seanterrill.com/category/brewing
twomilebrewing.com

Offline dzlater

  • Brewer
  • ****
  • Posts: 411
  • Dan S. New Jersey
    • View Profile
Re: calculating gravity adjustments during boil
« Reply #2 on: March 29, 2010, 03:45:38 AM »
Thanks
I got it all figured out.
Made a couple little programs for my calculator.
Dan S. from NJ

Offline dzlater

  • Brewer
  • ****
  • Posts: 411
  • Dan S. New Jersey
    • View Profile
Re: calculating gravity adjustments during boil
« Reply #3 on: March 29, 2010, 03:48:51 AM »
No calculator required IMHO.

G1*V1 = G2*V2

When adding extract, solve for G1. To dilute, solve for V2.

My problem was figuring out how much extract and how much to dilute.
Dan S. from NJ

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3568
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: calculating gravity adjustments during boil
« Reply #4 on: March 29, 2010, 08:00:37 PM »
If you need a hand with putting together a spreadsheet or anything, just let me know.
Beer is like porn. You can buy it, but it's more fun to make your own.
seanterrill.com/category/brewing
twomilebrewing.com

Offline denny

  • Administrator
  • Retired with too much time on my hands
  • *****
  • Posts: 13671
  • Noti OR [1991.4, 287.6deg] AR
    • View Profile
    • Dennybrew
Re: calculating gravity adjustments during boil
« Reply #5 on: March 30, 2010, 08:16:36 AM »
No calculator required IMHO.

G1*V1 = G2*V2

When adding extract, solve for G1. To dilute, solve for V2.

My problem was figuring out how much extract and how much to dilute.

Extract is pretty easy....1 lb. of DME will add about 9 points in 5 gal.  One lb. of LME will add about 7 points to 5 gal.
Life begins at 60.....1.060, that is!

www.dennybrew.com

The best, sharpest, funniest, weirdest and most knowledgable minds in home brewing contribute on the AHA forum. - Alewyfe

Offline dzlater

  • Brewer
  • ****
  • Posts: 411
  • Dan S. New Jersey
    • View Profile
Re: calculating gravity adjustments during boil
« Reply #6 on: March 30, 2010, 09:18:30 AM »
Thanks for all the help
I wrote three little programs for my TI85 calculator

the first program
you input, preboil gravity, preboil volume, and final volume
and gives the OG

the second program
you input, target gravity, target volume, preboil volume, and preboil gravity
and gives me lbs of DME to add, or the final volume needed to hit the OG

the third program
you input, final volume, target gravity, preboil volume
and gives the preboil gravity need to hit the OG
Dan S. from NJ

Offline bbump22

  • Assistant Brewer
  • ***
  • Posts: 124
    • View Profile
    • Bump City Brews
Re: calculating gravity adjustments during boil
« Reply #7 on: April 02, 2010, 10:47:25 AM »
dzlater - would you be willing to share the actual formulas if you find time?
mmmm....beer

Offline a10t2

  • Official Poobah of No Life.
  • *
  • Posts: 3568
  • Ask me why I don't like Chico!
    • View Profile
    • SeanTerrill.com
Re: calculating gravity adjustments during boil
« Reply #8 on: April 02, 2010, 01:00:51 PM »
I know I'm not dzlater (sorry!) but they would be:

1: OG = Vpre*SGpre/Vpost

2: DME (lb) = (Vpost/43)*(Vpost*SGpost - Vpre*SGpre)
    or: Vadd = (Vpost*SGpost/SGpre) - Vpre

3: SGpre = Vpost*SGpost/Vpre

In all cases, SG is in "points" (SG - 1).
Beer is like porn. You can buy it, but it's more fun to make your own.
seanterrill.com/category/brewing
twomilebrewing.com

Offline bbump22

  • Assistant Brewer
  • ***
  • Posts: 124
    • View Profile
    • Bump City Brews
Re: calculating gravity adjustments during boil
« Reply #9 on: April 13, 2010, 03:50:24 PM »
sweet, thanks!
mmmm....beer