Sunday, June 27, 2010

Notes on Gravity

Always read the Original Gravity (OG) before pitching the yeast. Measure the Final Gravity (FG) before bottling. After you bottle it the priming sugar will throw off the measurement and beyond that the carbonation would probably make it hard to read in addition to also having changed the density of the beer.

To calculate the approximate alcohol by volume (ABV) of the beer:
OG - FG * 129 = approximate alcohol by volume%
example: 1.045 - 1.015 = .030, .030 * 129 = 3.9%

Adjustments
Hydrometers tend to be manufactured for 60 degrees Fahrenheit (I wish I could find one that was designed to be read at room temperature!). So when reading the OG and FG some adjustment is usually required:

wort is 60F-No adjustment needed
70F-add 1 point
77F-add 2 points
84F-add 3 points
95F-add 5 points
105F-add 7 points

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