Calculating Grain Points (PPG)
Often referred to as grain points, or points per gallon (ppg) – This number represents the grains or adjuncts potential specific gravity for 1 lb of grains in one gallon of water.
If you know your grains potential SG, you can easily convert that value to PPG simply be grabbing the last 2 numbers of it’s potential specific gravity value.
Or to put it more simply…
A grain with a potential yield value of 1.035 = 35 Grain Points
If you are using the above calculator, these values have already been associated with the grains in the calculator. If you are doing these calculations by hand, you can find an exhaustive list of grains and their potential yield values via the Grains Chart.
If you are unable to find the potential value for any of the fermentable ingredients in your grain bill, there is an alternative formula that we can use that utilizes a grains DBFG (Dry Basis Fine Grind) or DBCG (Dry Basis Coarse Grind) value.
These values are typically supplied by the manufacturer, and can almost always be found by searching the manufacturers or suppliers website. For our example below, we’re going to be using Great Western Malting’s Premium 2 Row Malt, which has a DBFG value of 81%.
The first thing we have to do is define a reference number with a known yield value. The most efficient way to handle these calculations is to use our known yield (100%) value of pure sugar- aka sucrose.
In the example below we are simply taking the known potential value for sucrose and converting that number into what is often refered to as grain points or points per gallon (PPG).
1.046 – 1 = .046 * 1000 = 46
Now that we have our reference number of 46 PPG from sucrose, we need to multiply our known value for sucrose by the grains DBFG value of 81% to find our grains PPG value.
46 * .81 = 37.26
You can also use these same calculations to find your grains potential yield value using this simple conversion formula.
Potential = (37.26 / 1000) + 1
Potential Yield = 1.0373
Calculating a Recipes Potential Yield
Our next step is to find the average grain points for all of our recipes fermentable ingredients. To help illustrate the process I’ll be using one of my own personal favorites, my Modified HighRise IPA HomeBrew recipe.
- 6.5 lbs Maris Otter Pale Malt – 1.038 SG
- 6.5 lbs American Pale Ale Malt 2-Row – 1.037 SG
- 1.0 lb Orange Blossom Honey – 1.035 SG
- 0.5 lb Caramel Malt 40L – 1.034 SG
- 0.5 lb Victory Malt – 75% DBFG
First – Let’s find each grains PPG value.
Maris Otter Pale Malt = 38
American Pale Ale Malt 2-Row = 37
Orange Blossom Honey = 35
Caramel Malt 40L = 34Victory Malt: 46 * .75 = 34.5
Keep in mind that the PPG values above represent 1 lb in 1 gallon of water. So our next step will be to adjust the above values to fit our recipes ingredients and batch size using the following formula.
Total Grain Points = (Grain Points) * (Weight of Grain in Pounds) / (Batch Size in Gallons)
Now apply the above formula to our own recipe:
Maris Otter Pale Malt = ( 38 * 6.5 lbs / 5 gallons ) = 49.4
American Pale Ale Malt 2-Row = (37 * 6.5 lbs / 5 gallons ) = 48.1
Orange Blossom Honey = ( 35 * 1 lbs / 5 gallons ) = 7
Caramel Malt: 40L: = ( 34 * .5 lb / 5 gallons ) = 3.4
Victory Malt: = ( 34.5 * .5 lb / 5 gallons ) = 3.45
Once you’ve figured out the PPG values for each fermentable ingredient in your recipes grain bill, you simply add these values together to find your recipes potential yield.
49.4 + 48.1 + 7 + 3.4 + 3.45 = 111.35
Calculating a Recipes BrewHouse Efficiency
Once we know the recipes potential Specific Gravity ( 1.111 in this case ), we can calculate our brewhouse effieciency for the beer by applying our potential SG value for the recipe to the brewers actual Original Gravity. ( 1.083 )
83 / 111 = .7477 or 75%