• Let’s consider this.  
  • A standard drink contains about .60 ounces of pure alcohol, which is just a little more than a half an ounce.
  • A standard drink is a 12-ounce beer, a 5-ounce glass of wine, or a 1-1/2 ounce shot of 80-proof distilled spirits, all of which contain about the same amount of alcohol.
  • Proof is twice the percent of alcohol by volume.  
  • So, an 80-proof distilled spirit, such as in this example, has 40 percent alcohol by volume.
  • Keep in mind, these drink equivalents are approximations.
  • In reality, they will change if a person is drinking ale, malt liquors, fortified wines, port, brandy, different proof liquors, or if the person is drinking on an empty stomach, is tired, sick, upset, or had taken medicines or drugs.