Alcohol by Volume (ABV) Calculator
Calculate homebrew ABV from original and final gravity using ABV = (OG - FG) × 131.25.
Returns alcohol percentage, apparent attenuation, and grams per 12 oz.
ABV Formula (Standard):
ABV = (OG - FG) × 131.25
ABV Formula (More Accurate):
ABV = (76.08 × (OG - FG) / (1.775 - OG)) × (FG / 0.794)
Where:
- OG = Original Gravity — the density of your wort or must before fermentation begins. You measure this with a hydrometer or refractometer on brew day.
- FG = Final Gravity — the density after fermentation is complete. When the reading stays the same for 2-3 days in a row, fermentation has finished.
The standard formula is a quick estimate that works well for most homebrews. The advanced formula accounts for the changing density of alcohol in the solution and gives more accurate results, especially for high-gravity brews above 8% ABV.
Gravity Reference:
- Water = 1.000
- Typical beer OG: 1.035 - 1.090
- Typical wine OG: 1.070 - 1.120
- Typical mead OG: 1.080 - 1.130
Practical Example: If you brew a beer with OG = 1.055 and FG = 1.012: Standard: (1.055 - 1.012) x 131.25 = 5.64% ABV The advanced formula gives approximately 5.67% ABV for the same readings.
Common ABV Ranges:
| Style | ABV Range |
|---|---|
| Light beer | 3-4% |
| Regular beer | 4-6% |
| Strong beer/IPA | 6-10% |
| Wine | 11-15% |
| Mead | 8-18% |
Apparent Attenuation:
This tells you what percentage of sugars the yeast consumed.
Attenuation = (OG - FG) / (OG - 1.000) × 100%
Most healthy fermentations achieve 70-80% apparent attenuation.
Common Mistakes:
- Forgetting to temperature-correct your hydrometer reading (most are calibrated to 60F / 15.6C)
- Taking the FG reading before fermentation is truly complete
- Confusing Brix/Plato readings with specific gravity — they are different scales