Determine the alcohol by volume (ABV) of your homebrew beer, wine, or cider using original gravity (OG) and final gravity (FG) readings from a hydrometer.
ABV (alcohol by volume) is the universal standard for labeling how strong an alcoholic drink is — the percentage of total liquid volume that's pure ethanol. A 5% ABV beer is 5% ethanol by volume, the same way a 40% ABV vodka is 40% ethanol. For homebrewers, calculating ABV is one of the most basic and most important measurements you can make. It tells you how the fermentation went, whether the yeast finished its job, and how the batch compares to the recipe's target strength.
The math relies on a hydrometer reading taken before and after fermentation. Before yeast is pitched, the wort or must is dense with sugar — you measure its "original gravity" (OG), typically 1.040 to 1.100 for beer and 1.080 to 1.120 for wine. As yeast converts sugar into ethanol and CO₂, density drops. After fermentation ends, you take the "final gravity" (FG), typically 1.000 to 1.020. The difference between OG and FG tells you how much sugar was consumed, and from that you can estimate how much alcohol was produced.
This calculator uses the most common homebrewing formula (the "standard" or Daniels formula): ABV ≈ (OG − FG) × 131.25. For sweet wines and high-gravity beers where the simple formula overestimates, a more accurate formula by Balling-corrected DeClerck is also widely used. The error between formulas at typical beer strengths is under 0.5% ABV — close enough for most brewing decisions.
**Scenario:** You brew a 5-gallon American pale ale. OG was 1.054, FG measured 1.012 after 14 days. **Calculation:** ABV = (1.054 − 1.012) × 131.25 = 0.042 × 131.25 = 5.51%. Attenuation = (0.054 − 0.012) / 0.054 × 100 = 77.8%, a healthy result for US-05 yeast. **Result:** Finished beer is ~5.5% ABV with 77.8% attenuation. Solid pale ale numbers — comparable to commercial examples like Sierra Nevada Pale Ale (5.6%).
**Scenario:** A big imperial stout: OG 1.102, FG 1.025. Want a more accurate ABV than the simple formula. **Calculation:** Standard: (1.102 − 1.025) × 131.25 = 10.1%. Accurate: (76.08 × 0.077 / (1.775 − 1.102)) × (1.025 / 0.794) = (5.858 / 0.673) × 1.291 = 11.24%. Attenuation = 75.5%, good for a high-gravity stout where yeast is stressed. **Result:** True ABV is about 11.2% — the simple formula understates by 1.1 points. For commercial labeling or to track recipe accuracy on big beers, use the accurate formula.
**Scenario:** A red wine started at 1.092 OG and finished at 0.992 FG. **Calculation:** ABV = (1.092 − 0.992) × 131.25 = 13.13% by the standard formula. FG below 1.000 is normal for dry wine: ethanol is lighter than water, so when nearly all sugar is consumed the liquid becomes less dense than water. **Result:** A 13.1% ABV dry red. Wine yeasts (EC-1118, D-47, Premier Cuvée) routinely ferment to dryness, producing FGs of 0.990–0.998. The negative apparent extract is the ethanol replacing sugar by volume.
**Calculate ABV when:**
- **Brewing or winemaking at home**: ABV is the most basic quality control measurement. Use it to verify recipe targets and yeast performance. - **Recipe development**: scaling a recipe up or down? The same OG/FG math tells you whether your modifications maintained the target strength. - **Diagnosing a stuck fermentation**: if FG hasn't dropped enough for the OG, the yeast may have stopped early. Check yeast viability, temperature, and nutrient. - **Tracking attenuation by yeast strain**: lager yeasts often attenuate 75–82%; Belgian strains can go 80–90%; English ales 65–75%. Compare your numbers against published ranges. - **Comparing kit results to claims**: kits often advertise an ABV based on perfect attenuation. Real-world ABV is typically 0.3–0.8% lower. - **Labeling for friends or gifts**: even casual gifting benefits from accurate strength info, especially for high-ABV beverages.
**Some practical context for the numbers:**
| Style | Typical OG | Typical FG | Typical ABV | |---|---|---|---| | Light lager | 1.038 | 1.008 | 4.0% | | American pale ale | 1.052 | 1.010 | 5.5% | | IPA | 1.060 | 1.012 | 6.3% | | Russian imperial stout | 1.090 | 1.022 | 8.9% | | Barleywine | 1.100 | 1.026 | 9.7% | | Cider (dry) | 1.050 | 0.998 | 6.8% | | White wine | 1.090 | 0.993 | 12.7% | | Mead (semi-sweet) | 1.110 | 1.020 | 11.8% |
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ABV
5.25%
ABW
4.17%
Attenuation
80.0%
Calories (12oz)
~164
| Metric | Value |
|---|---|
| Original Gravity (Plato) | 12.4 P |
| Final Gravity (Plato) | 2.6 P |
| Apparent Attenuation | 80.0% |
| ABV | 5.25% |
| ABW | 4.17% |