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Apparent Attenuation

Apparent attenuation is the measurement of the percentage of sugars that have been converted to alcohol by the yeast in a beer. Apparent attenuation is equal to the original gravity minus the final gravity divided by the original gravity, showing the percentage of conversion. A typical apparent attenuation range is between 65 and 80%.


Apparent attenuation calculation example:

Original Gravity of sample beer =  1.06
Final Gravity of sample beer = 1.012
Calculation:  1.06 – 1.012 = .048
.048 / .06 = 80% Apparent Attenuation


There are a variety of ways to impact your apparent attenuation. Some of these include the type of yeast you use, the amount of yeast you pitch, your mash temperature(s), your grain bill composition, and your mash PH. If you are doing extract brewing, then the primary impacts will come from your yeast and any unfermentable sugars that you may add, such as maltodextrin.

Alcohol by Volume ABV

Alcohol by volume (ABV) represents what portion of the total volume of a liquid is alcohol.


To calculate the ABV of a beer,  you will want to subtract the Final Gravity from your Original Gravity and multiply by 131.


The following is an example of how to calculate your alcohol by volume, assuming that your original gravity was 1.055 and your final gravity reading was 1.012.


Here is an example: 1.055 – 1.012 = 0.043 x 131 = 5.633%
In this example your alcohol by volume worked out to 5.633%.

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