Calculate ABV from original and final gravity readings for homebrewing. Supports beer, wine, mead, and cider with attenuation and calorie estimates.
Alcohol By Volume (ABV) is the standard measure of alcohol content in a beverage, expressed as a percentage of total volume. For homebrewers, calculating ABV requires two gravity readings: the Original Gravity (OG) taken before fermentation begins, and the Final Gravity (FG) taken after fermentation is complete. The difference between these two measurements tells you how much sugar was converted to alcohol by the yeast.
The most commonly used formula is the simple ABV equation: ABV = (OG − FG) × 131.25. While this works well for most beers (under 6% ABV), it becomes less accurate for higher-gravity brews. For wines, meads, and strong ales above 8% ABV, more advanced formulas account for the non-linear relationship between gravity drop and alcohol production. This calculator uses the advanced formula for improved accuracy across all alcohol levels.
Beyond ABV, this tool calculates apparent attenuation (how much sugar the yeast consumed), real attenuation, calories per serving, and equivalent alcohol units. Whether you're brewing a light lager at 4% or a barleywine at 12%, this calculator gives you accurate results.
Accurate ABV is essential for labeling, responsible serving, recipe development, and knowing if your fermentation completed successfully. This calculator handles all gravity units and beverage types. Keep these notes focused on your operational context. Tie the context to the calculator’s intended domain. Use this clarification to avoid ambiguous interpretation. Align this note with review checkpoints.
Simple: ABV = (OG − FG) × 131.25. Advanced: ABV = (76.08 × (OG − FG) / (1.775 − OG)) × (FG / 0.794). Apparent Attenuation = (OG − FG) / (OG − 1) × 100%. Calories (12 oz) ≈ ((6.9 × ABW) + 4 × (RE − 0.1)) × FG × 3.55. Where ABW = ABV × 0.8, RE = Real Extract.
Result: 5.6% ABV, 78% apparent attenuation
OG 1.055 − FG 1.012 = 0.043 drop. Simple formula: 0.043 × 131.25 = 5.6% ABV. Advanced formula gives 5.64%. Apparent attenuation: (1.055 − 1.012) / (1.055 − 1) × 100 = 78.2%.
**Specific Gravity (SG):** The most common scale in homebrewing. Water = 1.000. A typical beer wort reads 1.040-1.070. Each point above 1.000 represents dissolved sugar. **Degrees Plato (°P):** Used widely in professional and European brewing. Measures sugar concentration by weight percentage. 1°P ≈ 4 gravity points (e.g., 12°P ≈ 1.048 SG). **Brix:** Primarily used in winemaking and cider. Same concept as Plato but calibrated for sucrose solutions. For grape must, Brix is standard.
**Light Lager:** 3.5-4.5% ABV. **American Pale Ale:** 4.5-6.0%. **IPA:** 6.0-7.5%. **Imperial IPA:** 7.5-10.0%. **Belgian Tripel:** 8.0-10.0%. **Barleywine:** 10.0-14.0%. **Table Wine:** 11.0-14.5%. **Fortified Wine:** 15.0-22.0%. **Mead (dry):** 10.0-14.0%. **Hard Cider:** 4.5-7.0%. Knowing where your calculated ABV should fall helps you verify that fermentation went as planned.
If your OG seems too low: your efficiency was poor, try adjusting your grain crush or mash duration. If FG is too high: fermentation may be stuck (raise temp, pitch more yeast, add yeast nutrient). If FG is lower than expected: the yeast may have consumed sugars you didn't intend (like dextrins in an overly fermentable wort). Wild yeast or bacterial contamination can also cause super-attenuation.
Original Gravity (OG) measures the sugar content of your wort/must before fermentation. Final Gravity (FG) measures what remains after yeast has converted sugar to alcohol. The difference determines ABV.
Use a hydrometer (floats in a sample at 60°F) or a refractometer (uses a few drops). Hydrometers are more reliable for FG since alcohol affects refractometer readings.
Not directly — alcohol changes the refractive index. You need a refractometer correction calculator to convert the reading. Hydrometers give accurate FG readings in beer/wine with alcohol present.
For beer: 1.008-1.016 is typical. Dry beers finish lower (1.002-1.006), sweet stouts higher (1.018-1.024). For dry wine: 0.990-0.998. For sweet wine: 1.010-1.030.
Attenuation is the percentage of sugars consumed by yeast. Apparent attenuation of 70-80% is typical for most beer yeasts. Higher attenuation means a drier beer. Belgian strains can reach 85%+.
A typical 5% ABV beer has about 150-170 calories per 12 oz serving. Higher ABV = more calories (both from alcohol and residual sugars). A 12% barleywine can have 350+ calories per 12 oz.