The calories hiding in alcoholic drinks
Alcohol provides roughly 7 calories per gram — more than carbohydrate or protein (4 calories per gram) and not far behind fat (9 calories per gram). Combined with the fact that most alcoholic drinks aren't required to carry nutrition labels in many jurisdictions, it's an easy source of calories to underestimate.
This calculator uses approximate calorie values for standard serving sizes: a 355ml beer (~5% ABV) at roughly 150 calories, a 150ml glass of wine (~12% ABV) at roughly 125 calories, and a 45ml spirit shot (~40% ABV) at roughly 100 calories — though actual values vary by specific brand and alcohol content.
Beyond the alcohol itself
This estimate covers the alcohol component only. Mixed drinks with sweetened sodas, juices, or syrups add substantial additional calories on top — a sugary cocktail can easily double or triple the calorie count of the alcohol alone.
Why these are sometimes called "empty" calories
Alcohol provides energy without the vitamins, minerals, or fiber that an equivalent amount of whole food would typically provide — a reason it's sometimes described as a source of "empty" calories, contributing to energy intake without much additional nutritional value.