Enter your Original Gravity (OG) and Final Gravity (FG) readings to calculate your beer’s alcohol content. Works with both hydrometer and refractometer readings.
How ABV Is Calculated
The standard formula used by homebrewers worldwide:
ABV = (OG − FG) × 131.25
This is the simplified version. For higher-gravity beers (above 1.080 OG), we also calculate using the more accurate alternate formula:
ABV = (76.08 × (OG − FG) / (1.775 − OG)) × (FG / 0.794)
Understanding Your Results
- Under 3.5% — Low/session strength. Great for all-day drinking.
- 3.5% – 5.5% — Standard strength. Most bitters, pales, and lagers.
- 5.5% – 7.5% — Strong. IPAs, strong bitters, Belgian styles.
- 7.5% – 10% — Very strong. Imperial stouts, barleywines, tripels.
- Over 10% — Extreme. Eisbocks, imperial everything, braggots.
Attenuation Explained
Apparent attenuation tells you what percentage of the available sugars your yeast converted. Most ale yeasts hit 72–78%, while lager yeasts and Belgian strains can push 80–90%. Low attenuation means a sweeter, fuller beer; high attenuation means a drier, thinner finish.
Tips for Accurate Readings
- Always temperature-correct your hydrometer readings (calibrated at 20°C / 68°F).
- Take OG after the boil, once the wort is cooled and well-mixed.
- Take FG when fermentation is completely finished — two identical readings 48 hours apart.
- If using a refractometer for FG, apply a refractometer correction factor (alcohol skews Brix readings).