Specific Gravity Question - Home Brew Forums

 Home Brew Forums > Specific Gravity Question

03-17-2010, 02:53 AM   #1
basie
Recipes

Mar 2009
Maryland
Posts: 7

Let's say I have 4.5 gallons of wort with an specific gravity of 1.064. If I were to add .5 gallons of water to that wort before adding the yeast, what is the new specific gravity and O.G. of this beer? Bonus points if you show your work.

Thanks HBTers!

03-17-2010, 03:15 AM   #2
Pappers_
Moderator

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Jan 2009
Chicago
Posts: 14,638
Liked 1841 Times on 1256 Posts

1.058

I didn't do any hand calculations - there is a dilution tool built into Beersmith. You should check it out - you can download it for free and use it during a trial period before purchasing it. Its really great, and Brad, the guy behind it, provides a great service. So many uses, including your question.

03-17-2010, 03:17 AM   #3
ajf
Senior Member

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Oct 2005
Long Island
Posts: 4,646
Liked 105 Times on 99 Posts

If you start with 4.5g at 1.064, you have 288 gravity points. That's 4.5 (gallons) * 64 (the meaningful part of 1.064)
Now you add 0.5g water (with an OG of 1.00) so you have 5 gallons, but the same number of gravity points, so divide 288 (gravity points) by 5 (total gallons) and you get 57.6 Convert that back to specific gravity, and you get 1.0576
Consider a gravity point as (the specific gravity - 1.000) * 1000 if you want to be mathematically correct.

-a.
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03-17-2010, 03:31 AM   #4
basie
Recipes

Mar 2009
Maryland
Posts: 7

Thanks Pappers and ajf!

Quote:
 Originally Posted by Pappers 1.058 there is a dilution tool built into Beersmith. You should check it out - you can download it for free and use it during a trial period before purchasing it. Its really great, and Brad, the guy behind it, provides a great service. So many uses, including your question.
Actually, I've paid for a registered copy of BeerSmith, and I agree that it's really great. Every time I use it I learn something new. I didn't know about the dilution tool, so thanks for the heads-up!