Definition - What does Brix mean?
Brix is the unit of measurement used to indicate a grape's level of ripeness. The level of brix determines the sugar levels and ripeness of grapes prior to and at harvest. Grapes are harvested between 21 and 25 degrees brix. This number also gives the winemaker an estimation of a wine's potential alcohol from the harvested grapes.
WineFrog explains Brix
Brix measurements inform the vintner and/or winemaker of the sugar level of their grapes prior to, and on, the day of harvest.
Once the grapes start showing signs of maturity, samples are taken about each week from the vineyard by selecting random grapes from randomly selected rows. The juices are mashed together and placed on the window of a spectrometer. By looking into the light, one can see the reading of the sugar levels in the juice to determine if and when the grapes may be ready for harvest.
On average, white grapes may be harvested from 21 to 25 degree brix and red grapes may be harvested at up to 28 degrees brix.
The potential alcohol levels for a wine from harvested grapes is calculated by multiplying the degree of brix by .55.