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I'm following a recipe from a book for an IPA that calls for the following (simplified) steps:

  1. Boil water (3G/11L)
  2. Add Light DME (1lb/450g) & return to boil
  3. Add hops
  4. At 45 mins, add LME (6.6lb/3kg)
  5. Add hops, etc & boil another 15 mins

I've put the malt ingredients into both Beer Calculus and BrewMate but the SG/OG I'm getting are way off. The book says I'm should expect 1.068 yet Beer Calculus is 1.049 & BrewMate is 1.048.

BC has the exact brands of extract, but BM does not, though that does not seem to make a noteworthy difference. I'm using the brands listed by the recipe (Briess).

The only thing I can see that's different from BM/BC and the recipe is that the calculators don't have any option for a late malt addition for the extract. Will the late addition cause a higher SG? Should I add more malt to kick it up? Or could there be something else at play?

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"boil size for the malt seems to be..." –  mdma Apr 11 '12 at 13:42
    
What's the batch size. I'm guessing 3 gallons is a partial boil. –  mdma Apr 11 '12 at 13:48

2 Answers 2

up vote 4 down vote accepted

A late malt addition doesn't affect final gravity. The only difference compared to a regular addition is that a 1 hour boil alters the flavor and color of the extract to a small degree. (The wort gravity will also be different for most of the boil, affecting hop utilization, but since the recipe states a late addition, this will have been taken into account.)

The different OG you're seeing must be because of a discrepancy in the recipe or the underlying PPG figures used in the calculators. My guess is your batch size is different from the recipe size.

I plugged the recipe into Beersmith and got 1.056 for 5 gallons, and 1.047 for 6 gallons. Beersmith gives DME a potential of 1.044 and LME 1.036. The other calculators are a point either way of these values, so you would only expect a few points difference in the final OG at most. To get up to the recipe's OG of 1.068, the target batch size has to be set to 4 gallons. (4.1 according to Beersmith.)

So, double check the recipe batch size that corresponds with what you are using in the beercalcs. If it's correct, then the recipe itself may have a misprint. Either way, simply scale up the values in proportion. E.g. to go from the 4 gallon batch to a 5 gallon, multiply the quantities by 1.25. To target 6 gallons, scale by 1.5.

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I've found 1.042 to be a better PPG for DME. But it's a small difference. –  Hopwise Apr 11 '12 at 15:13
    
The ROT is 45 ppg fpr DME and 36 ppg for LME. –  Denny Conn Apr 11 '12 at 15:15
    
I'm quoting ppg values from beersmith - made a small edit to make that point clearer. –  mdma Apr 11 '12 at 15:41
    
ROT? Can you explain that? –  Hopwise Apr 11 '12 at 18:14
    
Explain ROT or where 45 and 36 comes from? –  brewchez Apr 11 '12 at 22:21

Whats really screwed up is that for 5 gallons I get 1.057 which is right in the middle of your two (recipe OG and software OGs).

What more likely is that you didn't get a good mix when you added your 3 gallon wort to the two gallons of make up water. ( I am assuming this is a 5 gallon batch with a concentrated boil). The lack of accurate mixing has led to a lower than reality gravity measurement.

And no when sugar is added to the wort has no bearing on how many gravity points you get out of it.

From my math you can't get a 1.068 beer with that much extract. At three gallons you are in the 1.090 range.

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I don't think the OP has brewed this - just looking at expected OG from a couple of brewcalcs compared to that in the recipe. –  mdma Apr 11 '12 at 23:22

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