(Winemag) - When you purchase a bottle of wine, there’s no doubt that you’ve noticed certain things on the label, like the producer, appellation and a Surgeon General’s warning.

One thing required to be on a label (sort of) is the percent of alcohol by volume, or abv. You might be surprised, however, to learn the alcohol percentage listed is often not entirely true.

The truth is that the alcohol percentage on a wine label is more to serve the Alcohol and Tobacco Tax and Trade Bureau (TTB) than it is to serve you, the consumer. Here’s why.