Beer ABV Calculator
Calculate alcohol by volume (ABV) of beer from original gravity and final gravity readings
Result
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How to Use This Tool
Measure and record your beer's original gravity (OG) before fermentation using a hydrometer or refractometer.
After fermentation is complete, measure and record the final gravity (FG) from the same batch.
Enter the OG and FG values into the calculator fields, making sure they are in the same units (typically specific gravity like 1.050).
Click the 'Calculate ABV' button to instantly get your beer's alcohol by volume percentage.
Use the result for labeling, recipe feedback, or adjusting future batches.
What Is Beer ABV Calculator?
The Beer ABV Calculator is a simple yet essential tool for homebrewers and craft beer enthusiasts who want to know the alcohol content of their brew. By comparing the sugar density of the wort before fermentation (original gravity) to the density after fermentation (final gravity), the calculator estimates how much sugar yeast has converted into alcohol. Understanding ABV matters because it helps you monitor fermentation health, design balanced recipes, and comply with labeling requirements. Whether you're brewing a light session ale or a high-gravity imperial stout, knowing the exact ABV gives you confidence in your final product and allows for better quality control.
Formula
The calculator uses the standard formula: ABV = (OG - FG) × 131.25. OG (original gravity) is the specific gravity reading before fermentation, typically a number like 1.050. FG (final gravity) is the specific gravity after fermentation, e.g., 1.010. The difference between them represents the density change due to sugar conversion. Multiplying by 131.25 converts that difference into a percentage of alcohol by volume. For higher-gravity beers (above 1.060 OG), an alternate formula like (OG - FG) × 131 is sometimes used, but this tool applies the most widely accepted calculation for reliable results.
Tips for Best Results
🍺 Always calibrate your hydrometer to 60°F (15°C) or use a temperature correction chart to avoid skewed gravity readings.
🌡️ Take your final gravity reading after the beer has been stable for 3–4 days and check for consistency to ensure fermentation is truly complete.
📝 Keep a brewing log with OG, FG, and calculated ABV for each batch to track yeast performance and refine your recipes over time.
🔄 For beers with OG above 1.080, consider using the alternative formula (OG - FG) × 131 or a specialized high-gravity calculator for better accuracy.
Frequently Asked Questions
What do OG and FG mean?
OG stands for Original Gravity, the density of your wort before fermentation — it reflects the sugar content. FG stands for Final Gravity, the density after the yeast has consumed the sugars. The difference between them is what the calculator uses to determine alcohol content.
Why is temperature important when measuring gravity?
Hydrometers are calibrated at a specific temperature (usually 60°F). If your sample is warmer or colder, the reading will be off. Using a temperature correction chart or a hydrometer that auto-corrects ensures your OG and FG are accurate, which directly affects the ABV calculation.
Can I use this calculator for wine or mead as well?
Yes, the formula (OG - FG) × 131.25 works for any fermented beverage where you measure specific gravity before and after fermentation. However, note that very high-sugar musts may require an adjusted formula, so results for wine or mead should be treated as estimates.