Estimated OG
1.055
Original Gravity Calculator
Estimate the original gravity (OG) of a beer before brew day from the grain bill or malt extract, batch size, and your brewhouse efficiency. The calculator also projects final gravity and ABV from your yeast's expected attenuation.
Estimated FG
1.014
Estimated ABV
5.46%
55.4 points from the mash + 0.0 from extract and sugar = 55.4 gravity points
How the OG formula works
Gravity points: each fermentable has a potential in points per pound per gallon (PPG). 2-row pale malt is about 37, meaning one pound fully extracted into one US gallon gives 1.037.
Estimated OG:OG = 1 + Σ(lb × PPG × efficiency) ÷ gallons ÷ 1000. Efficiency applies to mashed grains only. Malt extract and sugars count at 100%.
FG and ABV: FG = 1 + (OG − 1) × (1 − attenuation), thenABV = (OG − FG) × 131.25. Check your yeast's listed attenuation, which is usually 70–80% for ale yeast.
PPG values are typical figures from John Palmer's How to Brew. Your maltster's spec sheet may list a slightly different potential or extract percentage.
10 lb of 2-row in 5 gallons at different efficiencies
| Brewhouse efficiency | Estimated OG |
|---|---|
| 60% | 1.044 |
| 65% | 1.048 |
| 70% | 1.052 |
| 75% | 1.056 |
| 80% | 1.059 |
Malt extract in 5 gallons
| Extract weight | LME (36 PPG) | DME (44 PPG) |
|---|---|---|
| 3 lb | 1.022 | 1.026 |
| 5 lb | 1.036 | 1.044 |
| 6 lb | 1.043 | 1.053 |
| 7 lb | 1.050 | 1.062 |
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FAQ
How do you calculate original gravity from a grain bill?
Multiply each grain's weight in pounds by its potential in points per pound per gallon (PPG), multiply by your brewhouse efficiency, add up the points, and divide by batch size in gallons. 10 lb of 2-row (37 PPG) at 72% efficiency in 5 gallons gives 10 × 37 × 0.72 ÷ 5 = 53 points, or OG 1.053.
What brewhouse efficiency should I use?
Many all-grain homebrewers land between 65% and 80%. Brew-in-a-bag setups often run 65–72%. If you are new to a system, start at 70% and adjust once you have measured a few batches.
Why is efficiency not applied to malt extract?
Extract and sugar dissolve completely, so all of their sugar ends up in the wort. Efficiency only describes how much sugar you rinse out of mashed grain.
Why does my measured OG differ from the estimate?
Different boil-off rates, a different final volume, grain crush, and mash temperature all change the result. Measure post-boil volume carefully, and correct your hydrometer reading for temperature.