Alcohol By Volume (ABV) Calculator
Enter your original and final gravity readings to find the alcohol by volume of your beer, wine, cider or mead — with both the simple and accurate formulas.
- ✓ Two formulas
- ✓ Working shown
- ✓ For all homebrew
Alcohol by volume
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ABV comes from two hydrometer readings. The original gravity (OG) measures the sugar in your liquid before fermentation; the final gravity (FG) measures what is left after the yeast has done its work. The standard formula is ABV = (OG − FG) × 131.25. Our default example, 1.050 → 1.010, gives 5.25% ABV.
The two formulas
Homebrewers use two formulas. The simple one is a straight-line approximation that is accurate for most beers:
The accurate formula (often credited to Michael Hall) corrects for the fact that the relationship curves at higher strengths, so it reads a little higher for strong beers, wines and meads:
Both are shown in the result above. Below about 6–7% they agree closely; above that, trust the accurate version.
Typical gravity ranges
| Drink | Typical OG | Typical FG | Approx. ABV |
|---|---|---|---|
| Light / session beer | 1.035–1.045 | 1.008–1.012 | 3.5–4.5% |
| Standard ale | 1.045–1.060 | 1.010–1.015 | 4.5–6% |
| Strong ale / IPA | 1.060–1.075 | 1.012–1.018 | 6–8% |
| Cider | 1.045–1.060 | 1.000–1.005 | 6–8% |
| Wine | 1.080–1.100 | 0.990–0.996 | 11–14% |
How to take the readings
Float a hydrometer in a sample of the liquid and read the gravity at the surface. Take the OG reading after mixing but before pitching yeast, and the FG reading once fermentation has finished — when the gravity has held steady for two or three days. Both readings should be temperature-corrected to your hydrometer's calibration temperature, usually 20 °C (68 °F), for best accuracy.
Bonus: apparent attenuation
The result also shows apparent attenuation — the percentage of sugar the yeast consumed, calculated as (OG − FG) ÷ (OG − 1) × 100. A well-fermented beer typically attenuates 70–80%. Low attenuation can mean a stuck fermentation or a sweeter, fuller body by design.
Frequently asked questions
How do you calculate alcohol by volume?
The standard homebrew formula is ABV = (OG − FG) × 131.25, where OG is the original gravity before fermentation and FG is the final gravity after. For example, (1.050 − 1.010) × 131.25 = 5.25% ABV.
What are OG and FG?
OG (original gravity) is the density of the liquid before fermentation, when it is full of sugar. FG (final gravity) is the density after the yeast has converted sugar to alcohol. The drop between them reveals how much alcohol was produced.
Why do two ABV formulas give slightly different answers?
The simple formula (× 131.25) is a linear approximation that is accurate up to about 6–7% ABV. The alternative formula corrects for the non-linear relationship at higher strengths, so strong beers and wines read a little higher with it.
What gravity should I aim for?
It depends on the drink. A session beer might start around 1.040 and finish near 1.010 for about 4% ABV, while a wine could start at 1.090 and finish at 0.995 for roughly 12–13% ABV.