Brewing ABV Calculator
Estimate alcohol by volume (ABV), apparent attenuation, and total alcohol in your batch from gravity readings.
Why an Alcohol Calculator Matters in Brewing
Whether you brew beer, cider, mead, or hard kombucha, tracking alcohol content is one of the most useful quality checks you can do. A reliable alcohol calculator helps you understand fermentation performance, compare recipes, and keep your process consistent from batch to batch.
In homebrewing, ABV is not just a number for labels. It also gives insight into how much sugar was converted by yeast, how dry a beer finished, and whether your mash or recipe is producing the expected strength.
How ABV Is Calculated from OG and FG
Original Gravity (OG)
OG is the density of your wort before fermentation starts. It reflects how much fermentable sugar is dissolved in the liquid. Higher OG usually means more potential alcohol.
Final Gravity (FG)
FG is the density after fermentation is complete. As yeast consumes sugars and produces alcohol, gravity drops. The difference between OG and FG is the key driver of ABV.
Common Formula Used in Brewing
This page uses two popular equations:
- Standard ABV estimate:
(OG - FG) × 131.25 - More advanced estimate:
(76.08 × (OG - FG) / (1.775 - OG)) × (FG / 0.794)
The advanced equation can be more accurate at higher gravities, while the standard estimate is quick and widely used in brewing software and recipe discussions.
How to Use This Brewing Alcohol Calculator
- Enter your OG reading.
- Enter your FG reading.
- Optionally add batch size to estimate total alcohol volume.
- Click Calculate.
You’ll get ABV estimates and apparent attenuation, plus alcohol volume if batch size is provided.
Tips for Better Accuracy
1) Correct for Temperature
Hydrometers are calibrated at specific temperatures (often 60°F/15.6°C or 68°F/20°C). Readings taken far from calibration temperature should be corrected.
2) Degas Samples for FG
Carbonation bubbles can lift a hydrometer and distort readings. Swirl your sample gently to release CO₂ before measurement.
3) Take Stable Readings
If FG is still dropping, fermentation is not done. Always verify with two similar readings across 24–48 hours.
4) Use Clean, Calibrated Tools
Hydrometers, refractometers, and thermometers drift over time. Quick calibration checks improve confidence in ABV numbers.
Typical ABV Ranges by Beverage Style
- Session Beer: 3.0%–5.0%
- Standard Ale/Lager: 4.5%–6.5%
- IPA: 5.5%–8.0%
- Imperial Styles: 8.0%–12.0%+
- Cider: 4.0%–8.0%
- Mead: 8.0%–14.0%+
Final Notes for Homebrewers
An alcohol calculator is a simple tool that can dramatically improve recipe repeatability. Keep a brew log with OG, FG, yeast strain, fermentation temperature, and packaging notes. Over time, your data will help you predict outcomes and brew exactly what you want.
Always brew and consume responsibly, and follow local laws for production, labeling, and distribution.