ABV Calculator
Calculate the Alcohol By Volume (ABV) of beer, wine, or cider from original and final gravity readings.
This free online abv calculator provides instant results with no signup required. All calculations run directly in your browser — your data is never sent to a server. Enter your values below and see results update in real time as you type. Perfect for everyday calculations, homework, or professional use.
Specific gravity before fermentation
Specific gravity after fermentation
Results
ABV
5.25%
Apparent Attenuation
80%
How to Use This Calculator
Enter your input values
Fill in all required input fields for the ABV Calculator. Most fields include unit selectors so you can work in your preferred unit system — metric or imperial, whichever matches your problem.
Review your inputs
Double-check that all values are correct and that you have selected the right units for each field. Incorrect units are the most common source of calculation errors and can produce results that are off by factors of 2, 10, or more.
Read the results
The ABV Calculator instantly computes the output and displays results with units clearly labeled. All calculations happen in your browser — no loading time and no data sent to a server.
Explore parameter sensitivity
Try adjusting individual input values to see how the output changes. This is a quick and effective way to develop intuition about how different parameters influence the result and to identify which inputs have the largest effect.
When to Use This Calculator
- •Use the ABV Calculator when you need accurate results quickly without the risk of manual computation errors or unit conversion mistakes.
- •Use it to verify calculations made by hand or in spreadsheets — an independent check can catch errors before they lead to costly decisions.
- •Use it to explore how changing input parameters affects the output — a quick way to develop intuition and identify the most influential variables.
- •Use it when collaborating with others to ensure everyone is working from the same numbers and applying the same assumptions.
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About ABV Calculator
Alcohol By Volume (ABV) is the standard measure of alcohol content in fermented beverages. For homebrewers and winemakers, ABV is calculated by measuring the specific gravity of the liquid before fermentation (Original Gravity, OG) and after fermentation (Final Gravity, FG). The difference between these two readings indicates how much sugar was converted to alcohol by the yeast. This calculator uses the widely accepted formula ABV = (OG - FG) x 131.25, which provides accurate results for most homebrew applications. It also calculates apparent attenuation, which tells you what percentage of the available sugars were fermented.
The Math Behind It
Formula Reference
ABV Formula
ABV = (OG - FG) x 131.25
Variables: OG = Original Gravity, FG = Final Gravity (hydrometer readings).
Apparent Attenuation
AA = (OG - FG) / (OG - 1) x 100%
Variables: Measures what percentage of sugars were consumed.
Worked Examples
Example 1: Standard pale ale
OG = 1.050, FG = 1.010
The beer has an ABV of 5.25% with 80% apparent attenuation.
Common Mistakes & Tips
- !Forgetting to take the original gravity reading before adding yeast.
- !Not correcting hydrometer readings for temperature (most hydrometers are calibrated at 60F).
- !Using the formula on high-gravity beers (above 1.090) where it becomes less accurate.
- !Confusing ABV (alcohol by volume) with ABW (alcohol by weight), which is about 20% lower.
Related Concepts
Frequently Asked Questions
What is original gravity?
Original Gravity (OG) is the specific gravity of the wort or must before fermentation begins. It indicates the amount of dissolved sugars available for the yeast to convert to alcohol. A higher OG means more potential alcohol.
How accurate is this formula?
The (OG - FG) x 131.25 formula is accurate within +/- 0.1% ABV for beers and wines up to about 8% ABV. For stronger beverages, use the more complex alternative formula for improved accuracy.
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