Alcohol By Volume Calculator
Free ABV calculator. Calculate alcohol content from original and final gravity readings for homebrewing beer, wine, mead, and cider.
ABV Calculator
Calculate alcohol content from gravity readings
Gravity Readings
Alcohol By Volume
5.25%
Standard Strength
4.2%
by weight
80.0%
High (dry finish)
554
per 12oz serving
10 g/L
approximate
Plato/Brix Conversion
Attenuation
Formula
Understanding Gravity Readings
Specific gravity measures the density of liquid compared to water (1.000). Sugary wort/must has higher gravity; as yeast converts sugar to alcohol, gravity drops. The difference tells us how much alcohol was produced.
Typical Gravity Ranges
- Light Beer: OG 1.035-1.045, FG 1.006-1.012
- Standard Beer: OG 1.045-1.060, FG 1.008-1.015
- Strong Beer: OG 1.060-1.090+, FG 1.010-1.020
- Dry Wine: OG 1.080-1.100, FG 0.990-1.000
- Mead: OG 1.090-1.140, FG varies by style
The ABV Formula Explained
The standard ABV formula used by homebrewers is straightforward:
Where OG is the original gravity reading before fermentation and FG is the final gravity after fermentation is complete. The constant 131.25 converts the gravity difference into an alcohol percentage by volume.
Worked Example
You brew an IPA with OG of 1.065 and FG of 1.012:
For higher gravity brews (OG above 1.080), some brewers use the alternate formula by Gosset: ABV = (76.08 × (OG - FG) / (1.775 - OG)) × (FG / 0.794). This accounts for the non-linear relationship between gravity and alcohol at higher concentrations. For most standard-strength beers, the simple formula is accurate enough.
Common Mistakes When Measuring ABV
Reading the hydrometer at the wrong point
Always read at the bottom of the meniscus (the curved surface of the liquid), not the top. The liquid clings slightly to the glass, creating a curve. Reading at the top can add 0.002-0.004 to your measurement, enough to throw off your ABV by 0.3-0.5%.
Skipping temperature correction
Hydrometers are calibrated at a specific temperature (usually 60°F / 15.6°C or 68°F / 20°C). A sample at 80°F reads about 0.002 lower than its true gravity. If you take OG from hot wort without correcting, your calculated ABV will be too low.
Taking FG too early
Fermentation can appear done while there is still active yeast at work. Always take two readings 48-72 hours apart. If they match, fermentation is finished. Bottling too early with residual sugar risks over-carbonation or bottle bombs.
Using a refractometer for FG without correction
Refractometers measure sugar concentration through light refraction. After fermentation, the alcohol in your sample bends light differently, giving a falsely high reading. You need a refractometer correction calculator to convert the Brix reading to true gravity when alcohol is present.
ABV by Style
Beer Styles
- Session/Light: 3-4.5%
- Pale Ale/Lager: 4.5-5.5%
- IPA: 5.5-7.5%
- Stout: 4-8%
- Belgian/Imperial: 7-12%+
Wine & Mead
- Dry Wine: 11-14%
- Sweet Wine: 8-12%
- Port/Dessert: 15-20%
- Dry Mead: 12-16%
- Sweet Mead: 10-14%
Cider & Seltzer
- Dry Cider: 5-7%
- Sweet Cider: 4-6%
- Hard Seltzer: 4-6%
- Kombucha: 0.5-3%
Frequently Asked Questions
How do I measure original gravity (OG)?
Use a hydrometer or refractometer on cooled wort/must before adding yeast. For hydrometers, ensure the sample is at the calibration temperature (usually 60°F or 68°F). Take the reading at the bottom of the meniscus.
When should I take final gravity (FG)?
Take FG when fermentation is complete - typically when gravity readings are stable for 2-3 consecutive days. For beer, this is usually 1-2 weeks; wine and mead may take longer. Don't rush this step.
What does attenuation mean?
Attenuation is the percentage of sugars consumed by yeast. Higher attenuation (75-85%) means a drier, less sweet finish. Lower attenuation (65-75%) leaves residual sweetness. Different yeast strains have different attenuation ranges.
How accurate is the ABV formula?
The standard formula (OG-FG)×131.25 is accurate within 0.1-0.2% for typical beers. For very high gravity brews (above 1.080 OG), more complex formulas may be slightly more accurate. Our calculator is sufficient for all practical purposes.
Why is temperature correction important?
Hydrometers are calibrated at specific temperatures (usually 60°F or 68°F). Warmer samples read lower than actual; colder samples read higher. Temperature correction ensures accurate gravity readings if you can't cool your sample.
What's the difference between ABV and ABW?
ABV (Alcohol By Volume) measures alcohol as a percentage of total volume. ABW (Alcohol By Weight) measures by mass. ABV is about 1.25× higher than ABW because alcohol is lighter than water. Most countries use ABV.
Can I use a refractometer instead of a hydrometer?
Yes, but with a caveat. Refractometers work perfectly for pre-fermentation OG readings. After fermentation, alcohol in the sample skews the reading, so you need to apply a correction factor. Many online calculators (including ours) can convert refractometer FG readings to true gravity. Hydrometers are more straightforward for FG measurements.
What if my final gravity is higher than expected?
A high FG usually means fermentation stalled. Common causes: yeast pitched too cold, insufficient yeast cells, low nutrient levels, or high-gravity wort that exhausted the yeast. Try raising the temperature by 2-3°F, gently swirling the fermenter, or pitching fresh yeast. Wait 48 hours and re-check gravity before concluding fermentation is done.
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