How much malt is really in a 1.040 beer? We need to understand how to use the PPG values associated with your malt, regardless of its source as grain, DME or LME. PPG stands for Points per Pound per Gallon. PPG relates the amount of gravity points contributed by one pound in one gallon of water. PPG bridges the gap between a “dry” ingredient (DME or grain) and the anticipated specific gravity of that ingredient once its in solution. Remembering that specific gravity as a number refers to the density of a liquid.
The best way to illustrate and conceptualize this in your mind is to think about a one-pound bag of DME. DME has a PPG of 44, or 44PPG. If you dissolved a one-pound bag of DME in on gallon of water it the resulting gravity would be 1.044 SG (specific gravity). Subsequently, an easier way to use this number is to ignore the gallon part of the equation. Before you add the water to your 1 pound of DME, that dry bag has 44 points in it (or 44 points per pound). Using easy math you can see that if you put that 44-point bag (one pound) in 2 gallons the 44 points would be diluted to a gravity reading of 1.022SG. Likewise, you can put that same 44 points into half a gallon and the resulting gravity would be 1.088SG (44/0.5 is 88). But the total points are always the same regardless of gravity readings. (22*2=44, 44*1=44 and 88*0.5=44)
How do we translate PPG numbers into 5-gallon batches? It may be easier if we think of recipe formulation in reverse. Let’s say you want to make a 5-gallon batch of 1.044 OG. A specific gravity of 1.044 can be taken to mean 44 points per gallon. So in a 5 gallon batch there is actually 5*44=220 total points. So to make that beer you need to get 220 total points of malt in there. If you were to make it entirely using DME, which is 44PPG, then you would need 5 pounds. 220 total points divided by 44 points per pound (ignore the gallon part of PPG because you already accounted for the gallons by calculating total points). 5 pounds makes sense because if 1 pound of DME in one gallon makes a 1.044 gravity wort, then it would take 5 pounds in 5 gallons to make the same strength beer.
Here is a tougher example:
You want to make a 6 gallon batch of 1.064 beer using LME. LME has a 37PPG rating.
The principle is the same for LME; just think of it as if it were a dry ingredient. You can do this because its PPG is lower because the water in the LME has already been accounted for, hence lowering the malts PPG from 44 to 37.
So for 6 gallons of 1.064 that would be 6*64 or 384 points needed. LME provides 37 points per pound, so 384/37 is 10.3 pounds of LME.
Being able to calculate anticipated gravity from the ingredients we use is critical to being able to formulate your own recipes, or more importantly to make changes in recipes you have. If you have a 1.040 beer and you think it would be better as 1.050 you’ll be able to calculate how much more DME to add to get there.
(BTW, for 5 gallons you would need 1.1 pound of DME to boost the gravity to 1.050)