ABV Calculator
Calculate the alcohol content of your homebrew by entering the original gravity (OG) and final gravity (FG) readings from your hydrometer.
Alcohol By Volume (ABV)
Alcohol Weight
Attenuation
Need to Calculate Cocktail ABV?
If you’re mixing drinks rather than brewing beer, try our Cocktail Alcohol Calculator to determine the exact alcohol content of your mixed drinks and cocktails. Perfect for bartenders and home mixologists!
Beer Alcohol By Volume Calculator
Calculate the alcohol content of your homebrew beer in just a few simple steps:
- Measure Original Gravity (OG): Take a hydrometer reading of your wort before fermentation begins. This measures the density of your wort compared to water and indicates the potential alcohol content.
- Measure Final Gravity (FG): After fermentation is complete, take another hydrometer reading. The difference between OG and FG shows how much sugar was converted to alcohol.
- Enter Values: Input both readings in the calculator fields above.
- Calculate: Click the button to see your beer’s ABV, alcohol weight, and attenuation percentage.
For accurate readings, ensure your hydrometer is calibrated and measurements are taken at the correct temperature (typically 60°F/15.6°C).
Understanding Your Results
Alcohol By Volume ABV Calculator (ABV)
ABV is the standard measurement for alcohol content in beverages. It represents what percentage of your beer’s total volume is pure ethanol. Most commercial beers range from 4-6% ABV, while craft and homebrews can vary widely from 3% to over 12%. Learn more about beer style guidelines and typical ABV ranges from the Brewers Association.
Attenuation
Attenuation refers to the percentage of fermentable sugars that your yeast consumed during fermentation. Higher attenuation results in drier, less sweet beers with higher alcohol content. Different yeast strains have different attenuation rates:
- 65-70%: Low attenuation (sweeter, fuller-bodied beers)
- 70-80%: Medium attenuation (balanced beers)
- 80-85%+: High attenuation (drier, more alcoholic beers)
Monitoring attenuation helps you understand your yeast performance and fermentation efficiency.
Common Beer Styles by ABV
Tips for Accurate Gravity Readings
- Always sanitize your hydrometer and testing vessel
- Remove carbonation from fermented samples by gently stirring or warming
- Take temperature readings and apply corrections if needed
- Use a hydrometer test jar for consistent sample volumes
- Read the meniscus at eye level for the most accurate measurement
When distilling spirits at home, it’s crucial to dilute your distillate to achieve the desired alcohol by volume (ABV) and ensure safety. This process involves measuring the alcohol content of your spirit and adding the appropriate amount of water. To simplify this calculation, you can use an online tool like the Alcohol Dilution Calculator
The Science Behind ABV Calculation
Our calculator uses the standard formula for determining alcohol content in beer:
ABV = (OG – FG) × 131.25
This formula works because:
- The difference between OG and FG represents fermentable sugars consumed
- During fermentation, yeast converts sugars primarily into ethanol and CO₂
- The 131.25 multiplier is derived from the specific gravity relationship between sugar and ethanol
For higher gravity beers (above 1.070), a slightly modified formula may be more accurate: ABV = (76.08 × (OG-FG) / (1.775-OG)) × (FG / 0.794)
For more advanced brewing science and techniques, the How to Brew website by John Palmer offers comprehensive guides on brewing calculations.
Factors Affecting Final ABV
Several brewing variables can influence your beer’s alcohol content:
- Mash Temperature – Higher temperatures (154-158°F) create less fermentable wort, resulting in lower attenuation and ABV
- Yeast Strain – Different strains have varying attenuation levels and alcohol tolerances
- Fermentation Temperature – Proper temperature control ensures optimal yeast performance
- Oxygenation – Adequate initial oxygen helps yeast multiply and ferment efficiently
- Nutrient Availability – Sufficient nutrients support complete fermentation
Frequently Asked Questions About Beer ABV Calculation
How do I use a hydrometer for OG/FG?
Sanitize equipment. Fill a test jar with wort (OG) or degassed beer (FG). Float the hydrometer, spin gently, and read the scale at the liquid’s surface (meniscus) at eye level. Record the temperature and apply corrections if needed (standard calibration is often 60°F/15.6°C). Stable FG readings over 2-3 days confirm fermentation is complete.
What’s the difference between ABV, ABW, and Proof?
ABV (Alcohol By Volume) is the standard for beer. ABW (Alcohol By Weight) is alcohol percentage by weight (roughly 80% of ABV). Proof (mainly for spirits) is twice the ABV (e.g., 40% ABV = 80 proof). Homebrew calculators focus on ABV.
Can I calculate ABV without OG?
Accurate calculation requires both OG and FG. Without OG, you can only estimate using brewing software or recipe details based on style/ingredients. Direct measurement is always best for precision.
Why is my ABV lower than expected?
Possible causes include incomplete fermentation (check FG stability), hydrometer errors (check calibration/temperature correction), poor yeast health/pitch rate, lack of oxygen at startup, or incorrect fermentation temperature.
How does mash temperature affect ABV?
Lower mash temps (148-152°F) create more fermentable sugars, leading to higher potential ABV and drier beer. Higher temps (154-158°F) create less fermentable sugars, resulting in lower potential ABV and fuller body.
Can I use a refractometer instead of a hydrometer for ABV calculations?
Yes, but carefully. Refractometers work well for OG. For FG, alcohol interferes with the reading, requiring a specific correction formula (use online tools/software) before using the value in an ABV calculator.
Simple vs. Accurate ABV Formulas
The common formula ABV = (OG – FG) * 131.25 is a good estimate, especially for mid-strength beers. More complex formulas exist for higher accuracy, particularly with high-gravity brews, often used by online calculators.
In Short Accurate ABV calculation relies on precise OG and FG measurements (using a hydrometer or corrected refractometer readings) and understanding fermentation factors. This empowers better brewing.