ABV formulas
Standard: ABV = (OG − FG) × 131.25
Alternative: ABV = 76.08 × (OG − FG) ÷ (1.775 − OG) × FG ÷ 0.794
Apparent attenuation = (OG − FG) ÷ (OG − 1) × 100
Worked example
A pale ale starts at 1.050 and finishes at 1.010. The standard formula gives (1.050 − 1.010) × 131.25 = 5.25% ABV. Apparent attenuation is 0.040 ÷ 0.050 = 80%.
Typical gravity ranges
| Drink | Typical OG | Typical FG | Typical ABV |
|---|
| Light lager | 1.028–1.040 | 0.998–1.008 | 2.8–4.2% |
| Pale ale | 1.045–1.060 | 1.010–1.015 | 4.5–6.2% |
| Stout | 1.036–1.075 | 1.007–1.018 | 4–7.5% |
| Hard cider | 1.045–1.065 | 0.995–1.010 | 5–8% |
| Dry wine | 1.080–1.100 | 0.990–0.998 | 11–14% |
| Mead | 1.080–1.120 | 0.990–1.020 | 8–14% |
Tips for accurate readings
- Spin the hydrometer gently to remove bubbles before reading.
- Read at the bottom of the curved surface (the meniscus), at eye level.
- Correct for temperature if your sample isn't at the calibration temperature.
- Fermentation is finished when the gravity stays the same for two or three days.
Home brewing laws differ by country and state, so check the rules where you live. This calculator is intended for adults of legal drinking age. Scaling a recipe? The ratio calculator can help.
Last reviewed October 2026.
Frequently asked questions
How do I calculate ABV from gravity readings?
Take a hydrometer reading before fermentation (original gravity, OG) and another when fermentation has finished (final gravity, FG). The standard homebrew formula is ABV = (OG − FG) × 131.25. For example, 1.050 to 1.010 gives (0.040) × 131.25 = 5.25% ABV.
Which formula is more accurate?
The simple formula is accurate enough for most beers up to about 6–7% ABV. For stronger beers, wines and meads, the alternative formula, ABV = 76.08 × (OG − FG) ÷ (1.775 − OG) × FG ÷ 0.794, usually gives a slightly higher and more accurate result. The calculator shows both.
What is apparent attenuation?
Apparent attenuation is the share of sugars the yeast appears to have fermented: (OG − FG) ÷ (OG − 1) × 100. Most ale yeasts reach about 70–80%. It is called "apparent" because alcohol is lighter than water, which makes the final reading a little lower than the true sugar content.
Do I need to correct for temperature?
Yes, if your sample is not at the hydrometer's calibration temperature, usually 60 °F or 68 °F (15.6 °C or 20 °C). Cool the sample or use the correction chart that came with your hydrometer before entering the readings.
Can I use a refractometer reading?
A refractometer reading taken before fermentation can be converted to gravity and used as OG. After fermentation starts, alcohol distorts refractometer readings, so use a hydrometer for the final gravity or a correction formula.