Alcohol carries 7 kcal per gram of pure alcohol (ethanol),1 and a US standard drink contains about 14 g of it,2 so one standard drink is about 98 kcal before any sugar or mixer is counted. Logging it is the awkward part: alcohol is not protein, fat or carbohydrate, so its calories have to be booked under a macro they do not belong to.
This article gives the arithmetic for any drink and the two ways to log the result. It is about counting, nothing else.
Seven kcal per gram
Food energy tables assign each energy source a factor per gram — 4 for protein and carbohydrate, 9 for fat and 7 for alcohol.1 Alcohol therefore sits between carbohydrate and fat in density, and unlike the three macros it is not a nutrient: it has calories and no target.
To get from a drink to grams of alcohol you need its volume, its strength (ABV, alcohol by volume, the percentage on the label) and the density of ethanol, 0.79 g/ml:
grams of alcohol = volume (ml) × ABV × 0.79 kcal from alcohol = grams × 7
What a standard drink is
The US standard drink is defined as 14 g (0.6 fl oz) of pure alcohol,2 and the "one drink" servings of beer, wine and spirits are the volumes that carry roughly that amount. Other countries define their units differently, so "a drink" is not a fixed calorie number across borders — the grams are what to count.
| Drink | Volume × ABV | Alcohol | kcal from alcohol | Also carries |
|---|---|---|---|---|
| US standard drink2 | — | 14 g | 98 kcal | — |
| Beer, 330 ml at 5% | 330 × 0.05 × 0.79 | 13 g | 91 kcal | carbohydrate (varies by style) |
| Wine, 150 ml at 12% | 150 × 0.12 × 0.79 | 14 g | 100 kcal | a little sugar in dry wine, more in sweet |
| Spirit, 40 ml at 40% | 40 × 0.40 × 0.79 | 13 g | 88 kcal | nothing — mixers are separate |
| Strong beer, 500 ml at 7% | 500 × 0.07 × 0.79 | 28 g | 194 kcal | carbohydrate |
The right-hand column is why a database entry for beer or a cocktail is usually higher than the alcohol arithmetic: the residual sugar, malt carbohydrate or mixer is real food energy on top.
In plain terms: work out the grams of alcohol, multiply by seven, then add whatever else is in the glass.
Logging it as carbs or as fat
Macro trackers have three gram targets. Alcohol fits none of them, so its calories are booked under one of the other macros so that the day's calorie total stays correct. Two methods:
| Method | Arithmetic for 98 kcal | What it does to the day |
|---|---|---|
| Log as carbohydrate | 98 ÷ 4 = 24.5 g carbohydrate | reduces the carbohydrate left for food by 24.5 g |
| Log as fat | 98 ÷ 9 = 11 g fat | reduces the fat left for food by 11 g |
| Split between the two | e.g. 12 g carbohydrate + 5.5 g fat | shares the reduction |
The carbohydrate method is the common choice, and it fits the MacroDiet formula: carbohydrate is the remainder macro on every style except keto, so it is the natural place for an unplanned energy source to land. On keto — where carbohydrate is a 30 g ceiling and fat is the remainder — the fat method fits better for the same reason.
Two rules keep the log honest. Never log alcohol under protein; protein is the one target set from body weight, and "filling" it with alcohol calories defeats the reason it exists. And be consistent: an adaptive expenditure estimate copes with a fixed habit far better than with a method that changes from week to week.
If your food database has entries that already carry the alcohol calories (a spirit at 98 kcal with 0 g macros, for example), log that entry as it is. The calorie total will be right and the macro lines will simply not sum to it, which is expected — see why macros don't add up to calories.
The short version
7 kcal per gram of alcohol;1 14 g in a US standard drink,2 so about 98 kcal before sugar or mixers; any drink is ml × ABV × 0.79 × 7. Log the calories as carbohydrate (÷ 4) on most styles or as fat (÷ 9) on keto, never as protein, and keep the same method every time. The macro calculator sets the three targets; alcohol is booked against them, not added to them.
Educational overview only — not medical advice. Zyra is a training and nutrition tracking tool; the numbers here are the algorithm's rules and published reference values, not an individual prescription.