ABV from OG and FG
Estimate alcohol by volume from a beer's original and final specific gravity.
Formula
ABV ≈ (OG − FG) × 131.25
Inputs
| Name | Unit | Description |
|---|---|---|
| OG | SG | Original gravity, measured before pitching yeast. |
| FG | SG | Final gravity, measured after fermentation is complete. |
Outputs
| Name | Unit | Description |
|---|---|---|
| ABV | % v/v | Alcohol by volume. |
Worked example
Inputs:
- OG = 1.052
- FG = 1.01
Calculation:
(1.052 − 1.010) × 131.25 = 0.042 × 131.25
Result:
5.51 % ABV
Sample values
| OG | FG | ABV (% v/v) |
|---|---|---|
| 1.038 | 1.01 | 3.68 |
| 1.045 | 1.01 | 4.59 |
| 1.052 | 1.012 | 5.25 |
| 1.06 | 1.015 | 5.91 |
| 1.075 | 1.018 | 7.48 |
When to use this
The simple linear formula above is accurate to within a tenth of a percent for typical beers up to around 7 % ABV. For higher-strength beers, a corrected (non-linear) form gives slightly better results, but for a homebrew kitchen the simple form is fine.
Learn more
- Fermentation basicsHow yeast turns wort into beer, what temperature and pitch rate do, and what to watch for during primary fermentation.
- Fermentation control — temperature, schedule, packagingWhy fermentation temperature is the single most important brew-day variable, and how to manage it on a homebrew budget.