Grain Bill Calculator — All-Grain & Extract
Build your grain bill or extract recipe and instantly see the estimated original gravity (OG), beer color in SRM, and total fermentable weight. Switch between all-grain (default 75% efficiency) and extract (default 95%) modes to match your brewing setup.
Fermentables
Results
How the grain bill calculator works
For each fermentable, enter the weight in pounds and its potential gravity points (PPG) — the points-per-pound-per-gallon yield at 100% efficiency. Typical PPG values: 2-row base malt 36–37, Munich 35, Crystal 34, DME 44, LME 36, Honey 35, Corn sugar 46.
Estimated OG = (Σ(weight × PPG) × efficiency) ÷ batch size, then converted from gravity points to specific gravity.
SRM (color) is calculated using the Morey equation: SRM = 1.4922 × MCU0.6859, where MCU = Σ(grain Lovibond × weight) ÷ batch size.
Common Fermentable Reference
| Fermentable | PPG | °L (color) |
|---|---|---|
| 2-Row Pale Malt | 37 | 1.8 |
| Pilsner Malt | 37 | 1.5 |
| Munich Malt | 35 | 10 |
| Vienna Malt | 35 | 4 |
| Wheat Malt | 38 | 2 |
| Crystal 40L | 34 | 40 |
| Crystal 60L | 34 | 60 |
| Crystal 120L | 33 | 120 |
| Chocolate Malt | 28 | 350 |
| Roasted Barley | 25 | 500 |
| Flaked Oats | 33 | 1 |
| Dry Malt Extract (light) | 44 | 4 |
| Liquid Malt Extract (light) | 36 | 4 |
| Honey | 35 | 2 |
| Corn Sugar (dextrose) | 46 | 0 |
How This Calculator Works
Every fermentable carries a potential extract figure expressed as PPG — points per pound per gallon, the gravity points one pound yields in one gallon of water at 100% extraction. The calculator multiplies each grain's weight by its PPG, adds them up, then scales the total by your efficiency: OG points = (Σ(weight × PPG) × efficiency) ÷ batch volume. Those points become specific gravity with SG = 1 + (points ÷ 1000), so 55 points reads as 1.055.
Color uses the Morey equation. First it finds Malt Color Units, MCU = Σ(weight × °Lovibond) ÷ batch volume, then converts with SRM = 1.4922 × MCU0.6859 — a logarithmic curve that mirrors how a few ounces of dark malt deepen color far less at the dark end than the light end.
A Worked Example
Take a classic amber ale into a 5-gallon batch at 75% efficiency: 9 lb of 2-row pale malt (37 PPG, 1.8 °L) and 1 lb of Crystal 40L (34 PPG, 40 °L).
Gravity points at 100% are (9 × 37) + (1 × 34) = 333 + 34 = 367. Apply 75% efficiency: 367 × 0.75 = 275. Divide by 5 gallons = 55 points per gallon, an OG of 1.055. For color, MCU = ((9 × 1.8) + (1 × 40)) ÷ 5 = 56.2 ÷ 5 = 11.24, so SRM = 1.4922 × 11.240.6859 ≈ 7.8 SRM — a deep gold to light amber. Drop efficiency to 70% and that same bill falls to about 1.051.
What Affects Your Result
- Mash efficiency — the biggest variable in all-grain brewing. Crush fineness, mash thickness, mash time, and sparge technique all move it several points.
- Crush quality — a tighter mill gap exposes more starch and raises extraction, but crush too fine and you risk a stuck sparge.
- Mash pH — conversion is most efficient between pH 5.2 and 5.6; drift outside that band and yield suffers.
- Measured batch volume — gravity is points per gallon, so over- or under-shooting your volume shifts OG directly.
- Malt freshness and lot variation — published PPG values are averages; real malt varies, and stale or poorly stored grain yields less.
- Mash temperature — while it barely changes OG, mashing hot (156–158°F) leaves more unfermentable dextrins, raising final gravity and body.
Frequently Asked Questions
What brewhouse efficiency should I enter?
Most all-grain homebrewers land between 65% and 80%, and 72–75% is a sensible default for a single-infusion mash with a moderate crush. If you have brewed the same system before, use your measured number: divide the points you actually hit by the points this tool predicts at 100%, and enter that. Extract brewers should use 90–95%, since extract is already converted.
Why is my actual OG lower than the calculated OG?
Usually lower mash efficiency — a coarse crush, under-mixed or short mash, or a mash pH outside 5.2–5.6. Volume errors matter too: collect more wort than your target and the same sugar is diluted across more liquid, dropping gravity. Re-measure post-boil volume and check your mill gap before blaming the grain.
What is the difference between PPG and degrees Lovibond?
PPG is sugar yield — how many gravity points a pound adds per gallon. Degrees Lovibond is color only. Roasted barley is just ~25 PPG but 500 °L, so a few ounces blacken a stout without adding much gravity.
Can I use this for extract or partial-mash recipes?
Yes. Switch to extract mode (95% default) and enter DME at ~44 PPG or LME at ~36. For partial mash, add your steeped and base grains at mash efficiency plus the extract as separate lines — the calculator sums them all.