Standard Drink Calculator
How it works
The amount of pure alcohol in the pour is volume × (ABV ÷ 100), in fluid ounces. Dividing that by 0.6 — the US standard drink — gives the count shown: a 12 fl oz beer at 5% ABV contains 0.6 fl oz of pure alcohol, which is exactly one standard drink.
The same maths works for any volume and strength, from a small strong pour to a large weak one, which is the point of measuring in standard drinks rather than in glasses or cans.
Already know your standard-drink count and want to estimate blood alcohol content from it? See the Blood Alcohol Content Estimator.
Frequently asked questions
Why is a "standard drink" a fixed amount of alcohol rather than a fixed drink size?
Because beverages themselves vary enormously in strength: a strong craft beer and a light beer can be the exact same glass size and still contain very different amounts of actual alcohol. Defining the standard drink as a fixed 0.6 fl oz of pure alcohol is what makes drink counts comparable across beer, wine and spirits at all — a fixed beverage size could not do that.
Where do typical ABV values come from?
The label. This calculator suggests ~5% for beer, ~12% for wine and ~40% for spirits as starting points because they are common, but actual products vary a fair amount either side of those — a strong IPA or a fortified wine can be well outside the typical range. Checking the label gives an exact answer instead of a rule of thumb.
How does this feed into the BAC Estimator?
The Blood Alcohol Content Estimator takes a standard-drinks count as its own input, so this tool is the step before that one whenever you know a pour's volume and ABV rather than already knowing how many standard drinks it works out to.