Attenuation

Rea­dings
°P
SG
%gew
SG
Results
%gew
SG
%vol
%gew
%
%
kcal
kJ

Calculation of Attenuation and Alcohol Content

To cal­cu­la­te the atte­nua­ti­on plea­se fill in the ori­gi­nal and final gra­vi­ty of your beer mea­su­red by a hydro­me­ter (if you use a refrac­to­me­ter, the values mus be con­ver­ted or bet­ter used in the refrac­to­me­ter cor­rec­tion page).

When you mea­su­re the final gra­vi­ty of your beer using a hydro­me­ter, the value is tam­pe­red by the alco­hol. So this is only an appa­rent gra­vi­ty. Howe­ver, if you know the ori­gi­nal gra­vi­ty you can cal­cu­la­te the real gravity.

The alco­hol be weight can be cal­cu­la­ted from the dif­fe­rence of ori­gi­nal and final gra­vi­ty. The alco­hol by volu­me is cal­cu­la­ted with the help of the density.

The atte­nua­ti­on desci­bes the por­ti­on of the ori­gi­nal gra­vi­ty that can be fer­men­ted by the yeast. The appa­rent atte­nua­ti­on is cal­cu­la­ted with the appa­rent gra­vi­ty; the real atte­nua­ti­on with the real final gravity.

The ener­gy con­tent is buil­ded from the alcohol’s ener­gy and the resi­du­al extract, in which the alco­hol out­weighs by far.

Sources:

  1. Hubert Hang­ho­fer: Bier brau­en nach eige­nem Geschmack, S. 125