Gravity points = grain's extract potential (EP) x mass (lbs) = specific gravity x volume.
Calculating for Malt Extracts:
To brew 5 gal of 1.043 gravity beer, you need 215 total gravity points (5 gal x 43 points).
• use 5 lbs of DME having 43 points (215 total gravity points / 43 ppg = 5 lbs DME), or
• use 5.97 lbs of LME having 36 points (215 total gravity points / 36 ppg = 5.97 lbs LME).
Calculating for Specialty Grain Additions:
To calculate the addition from specialty grains, assume 35% BE of the grain's EP.
• 1.3 lb. Crystal 77L having 1.034 EP, ((34 EP x 1.3 lb.) x 0.35 BE) / 5 gal = 3 points, or
• 15.47 additional total gravity points / 5 gal = 3 points (1.003 ppg) addition.
Calculating for All-Grain Mash:
To calculate gravity for an all-grain mash (5 gal batch volume), assume 75% BE of the grain's EP.
• 9 lbs Maris Otter having 1.038 EP, ((38 EP x 9 lbs) x 0.75 BE) / 5 gal = 51 points, or
• 256.5 total gravity points / 5 gal = 51 points (1.051 ppg).
BE = Brewhouse Efficiency, may vary with brewing techniques, so adjust accordingly.
EP = extract potential, how much sugar, thus gravity, to expect from a grain.
PPG = specific gravity points per pound per gallon.