ABV Calculator (OG/FG)

Calculate alcohol by volume, apparent attenuation, and calories per serving from original and final gravity readings.

Inputs

Original Gravity (OG)

Final Gravity (FG)

Tab to move between fields

Results

Alcohol by Volume

5.25%

Apparent Attenuation80%

Real Attenuation65.5%

Calories (12 oz)112 cal

How to Use This Calculator

Measure wort specific gravity before fermentation with a hydrometer or refractometer and enter as Original Gravity (OG).
After fermentation is stable (same reading 2–3 days in a row), enter Final Gravity (FG).
Review ABV (%), Apparent Attenuation (%), Real Attenuation (%), and Calories per 12 oz.
Use the ABV vs. Final Gravity line chart to see how alcohol content changes across a range of FG values.

How the result changes with Original Gravity (OG)

Original Gravity (OG)	Alcohol by Volume
1.01	0%
1.05	5.25%
1.1	11.81%
1.14	17.06%

What each input means

Original Gravity (OG): Specific gravity reading before fermentation. Take a hydrometer or refractometer reading of cooled wort.
Final Gravity (FG): Specific gravity reading after fermentation is complete. Stable over 2-3 days means fermentation is done.

How this is calculated

Worked example, using the default values

Identify Input Parameters
Original Gravity (OG) = 1.05, Final Gravity (FG) = 1.01 = 2 input(s) provided
Calculate Alcohol by Volume
Alcohol by Volume
5.25 = 5.25
Calculate Apparent Attenuation
Apparent Attenuation
80 = 80
Calculate Real Attenuation
Real Attenuation
65.5 = 65.5

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