estimating original gravity - Home Brew Forums

 Home Brew Forums > estimating original gravity

11-12-2006, 03:57 AM   #1
Jack
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Aug 2006
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I was just wondering... Is there an equation that allows you to estimate original gravity given the amount of extract that you use? I've had some batches that had a lower OG than I wanted, so I make a note to increase the amount of DME the next time I brew.

11-12-2006, 04:17 AM   #2
todd_k

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11-12-2006, 06:48 AM   #3
Jack
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I sort-of found an answer to my original question on The Google, but I'd still be interested in hearing if anyone has any equations that they've found useful in recipe formulation.

On page 153 of the third edition Joy of Homebrewing (it's not numbered), Papazian says to make an ESB with 7 lbs LME. Using John Palmer's handy-dandy conversion between LME and DME, this works out to 5.6 lbs DME. When I made it this way the first time, the OG was only 1.042. When I bumped the DME to 6 lbs, it was 1.045. But it's still not at the 1.052 - 1.056 that Papazian says is appropriate for the style.

Both have been good beers, but I feel like I should call it a Special Bitter instead of an ESB if I can't get my OG to be higher.

The recipe the last time I made it was:
1 lb 60L crystal malt
6 lbs light DME
2.5 oz whole Kent goldings (60)
0.5 oz whole Kent goldings (30)
0.5 oz whole Kent goldings (15)
5 gallons water

11-12-2006, 07:06 AM   #4
Yuri_Rage
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Your question kinda depends on the fidelity you want. I can roughly estimate the OG of all of your beers to be between 1.000 and 1.300 without ever seeing the recipe.

Seriously, though, the best way I can find to estimate the results of a recipe is by using some brewing software. I use BeerSmith, but I'm seriously considering a switch to Beer Tools Pro.

BeerSmith puts your recipe at 1.058.
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11-12-2006, 07:57 AM   #5
Jack
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You know... there's got to be an obvious explanation...

In the last few minutes of the boil, I top off my brew pot to compensate for the volume that evaporated.

Am I not supposed to do that?

11-12-2006, 09:17 AM   #6
Torchiest

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Quote:
 Originally Posted by Yuri_Rage Seriously, though, the best way I can find to estimate the results of a recipe is by using some brewing software. I use BeerSmith, but I'm seriously considering a switch to Beer Tools Pro. BeerSmith puts your recipe at 1.058.
I've been using Beer Smith, and I'm really impressed with it, but I've only had it for a few weeks. Why do you think Beer Tools Pro is superior?
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11-12-2006, 11:22 AM   #7
the_bird
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Same question regarding BPT. I have three days left of my free BeerSmith trial, I have to make a decision.
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11-12-2006, 11:30 AM   #8
chillHayze

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Quote:
 Originally Posted by the_bird Same question regarding BPT. I have three days left of my free BeerSmith trial, I have to make a decision.
I'm wondering, too. I bought the BeerSmith, and wasn't really impressed with BT online. Is BTP a downloadable program, or is it just the quirky, slow drop-down menu based BT with more features?
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11-12-2006, 03:08 PM   #9
david_42

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OP - topping off could be the problem. A seemingly small amount of water can shift your OG a lot. Most recipes have you start with a little extra water (boil volume in most software), so you end up with 5 gallons, but I've had a few that start with 5, finish short and hit the OG exactly. Unlike many experienced brewers, I frequently do clone kits for variety . This requires following the directions exactly.
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