Alcohol by Volume
The percentage of the ALCOHOL content by volume in a wine must, by United States law, appear on every wine label. However, because alcohol can be difficult to measure precisely and because wineries often need to print their labels before they know the exact alcohol content, the percentage stated on the label need only be accurate within 1.5 percent as long as the amount is not more than 14 percent. If greater than 14 percent, it must be accurate to within 1 percent. For example, a wine labeled 12 percent alcohol by volume may contain anywhere from 10.5 to 13.5 percent alcohol.