AleArchive | Calculators | Apparent Attenuation

Apparent Attenuation Calculator

This calculator determines the apparent attenuation achived during a fermentation using original gravity (OG) and final gravity (FG) readings.


Gravity Units:


About this Calculator

This calculator uses two gravity readings to determine the apparent atteunation of a finsished beer. The first gravity reading, also called the original gravity (OG), should be taken prior to the start of any fermentation activity. The second gravity reading, or final gravity (FG), should be taken after fermentation has finished.

The formula used for this calculation requires gravity units to be expressed in terms of specific gravity. However, the option is provided for the user to provide gravity readings in terms of degrees Plato. If inputs are provided in degrees Plato are provided, these readings are first converted to specific gravity using the methodology explained in the SG to Plato Calculator.

Apparent Attenuation Calculation

The formula used for this calculation is as follows:

Apparent Attenuation (%) = (OG - FG) / (OG - 1) * 100

In this formula OG represents the original gravity reading in specific gravity units and FG reprsents the final gravity reading, also in specific gravity units.