Homebrew ABV Calculator (Original and Final Gravity)
Enter the original gravity before fermentation and the final gravity after.
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Your results
Homebrew ABV Calculator (Original and Final Gravity) by TheCalcTools
How the Homebrew ABV Calculator (Original and Final Gravity) works
Yeast turns sugar into alcohol and CO₂, so the density (gravity) falls. The usual homebrew formula ABV = (OG − FG) × 131.25 works well up to about 8%.
For stronger drinks the alternative formula 76.08 × (OG − FG) ÷ (1.775 − OG) × FG ÷ 0.794 is more accurate. Correct hydrometer readings for temperature first.
The formula
Worked example
Using the default values shown in the calculator:
| Original gravity (OG) | 1.055 |
|---|---|
| Final gravity (FG) | 1.012 |
- OG 1.055 to FG 1.012: ABV 5.64%, apparent attenuation 78.2%.
Result:
| ABV (standard formula) | 5.64% |
|---|---|
| ABV (formula for strong beers, wines and meads) | 5.79% |
| Apparent attenuation | 78.2% |
| Alcohol by weight (approx.) | 4.42% |
Frequently asked questions
Can I use a refractometer for final gravity?
Not directly: alcohol skews refractometer readings after fermentation, so a correction formula is needed.
Sources and further reading
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This calculator gives estimates for information only. Check important results independently before you rely on them. See our disclaimer.