Use this calculator to estimate the alcohol by volume of your beer based on the gravity change before and after fermentation. If you recorded your original gravity (OG) and your final gravity (FG) before adding priming sugar at bottling, you can quickly calculate the approximate ABV of your batch.
You can also explore our related brewing tools, including the Hydrometer Temperature Adjustment Calculator and Brix Converter.
How Beer ABV Is Calculated
Original Gravity (OG) shows how much fermentable sugar is present in the wort before fermentation begins. Final Gravity (FG) shows how much sugar remains after fermentation is complete. The difference between these two readings helps estimate how much alcohol was produced.
In general, a lower FG suggests a drier, crisper beer, while a higher FG may indicate a fuller, sweeter profile.
ABV Formulas
Standard ABV Formula
ABV = (OG – FG) × 131.25
Alternate ABV Formula
ABV = (76.08 × (OG – FG) / (1.775 – OG)) × (FG / 0.794)
If you are not sure which method to use, the standard formula is the easiest and most common choice for homebrewers.
Additional Brewing Stats
This calculator can also help you review other useful brewing values, such as:
- Apparent attenuation
- Estimated calories
- Original Gravity in Plato and Specific Gravity
- Final Gravity in Plato and Specific Gravity
Keep in mind that hydrometer readings should be temperature-corrected for better accuracy.
Brewing Terms Explained
Original Gravity (OG)
The gravity of wort before fermentation. It reflects the amount of fermentable sugar available to the yeast and helps estimate the potential strength of the beer.
Final Gravity (FG)
The gravity of beer after fermentation is finished. It indicates how much sugar remains and helps define the final body, sweetness, and dryness of the beer.
Specific Gravity (SG)
A measurement of liquid density compared to water. Brewers use SG to monitor fermentation and calculate beer strength.
Alcohol by Volume (ABV)
The percentage of alcohol in the finished beer. It is one of the most common ways to describe beer strength.
Hydrometer
A brewing tool used to measure specific gravity. It is essential for tracking fermentation and calculating ABV.
Refractometer
A compact tool that measures sugar concentration from a very small sample. It is useful for quick readings during the brewing process.
Attenuation
The percentage of sugars converted by yeast into alcohol and carbon dioxide during fermentation. It helps show how efficiently the yeast performed.
Fermentation
The stage where yeast transforms sugars in wort into alcohol, carbonation, and flavor compounds, turning wort into beer.
Liberty Craft Journal Note
At Liberty Craft Journal, we build practical brewing tools and easy-to-understand guides for beer enthusiasts, homebrewers, and curious readers who want to understand what happens in every batch, from first gravity reading to final pour.