How much protein is in black coffee?

Black coffee has 0.1 g of protein per 100 g and 0.2 g per 6 fl oz (178 g). That is 10 g of protein per 100 kcal — a solid protein-per-calorie ratio for a whole food.

Where do these calorie figures come from?

USDA FoodData Central record 171890, “Beverages, coffee, brewed, prepared with tap water” (SR Legacy, FDC SR Legacy 2018-04 + FNDDS 2024-10-31). Energy is USDA nutrient 1008 (Energy, kcal); protein, fat and carbohydrate are read from the same record. USDA data is in the public domain, and the FDC ID above links straight to it.

All foods

Coffee and teaUSDA SR LegacyFDC 171890

Calories in black coffee

USDA FoodData Central record for “Beverages, coffee, brewed, prepared with tap water” — per 100 g, per every USDA serving size, and next to the other coffee and tea rows.

The short answer

Black coffee: 1 kcal per 100 g. 6 fl oz (178 g) is 2 kcal with 0.2 g of protein. Source: USDA FoodData Central record 171890, "Beverages, coffee, brewed, prepared with tap water".

Per 100 g

Nutrient	Per 100 g	Share of energy
Energy	1 kcal	100%
Protein	0.1 g	40%
Fat	0 g	0%
Carbohydrate	0 g	0%
Alcohol	—	60%

Black coffee is 1 kcal per 100 g in USDA FoodData Central (SR Legacy). Of that energy, about 40% comes from protein, 0% from fat and 0% from carbohydrate, and 60% from alcohol. That works out to 10 g of protein per 100 kcal — a solid protein-per-calorie ratio for a whole food.

Per serving

The serving sizes USDA lists for this record, priced from the per-100 g figures above. Nothing here is rounded to a “portion” — the gram weight next to each label is what the calories are computed from.

Serving	Weight	Calories	Protein
100 g	100 g	1	0.1 g
6 fl oz	178 g	2	0.2 g
1 cup (8 fl oz)	237 g	2	0.2 g

Compared with other coffee and tea

Food	kcal / 100 g	Protein / 100 g	Per serving
Black coffee	1	0.1 g	2 kcal · 6 fl oz
Black tea	1	0 g	2 kcal · 6 fl oz

Worth knowing

Brewed black coffee is about 1 kcal per 100 g — effectively zero. Every calorie in a coffee order is milk, cream, syrup or sugar; a latte is a glass of milk with coffee in it.

Other tables in beverages

The same numbers for the foods this one usually shares a plate — or a shopping list — with.

Questions about black coffee

How many calories are in black coffee?: Black coffee: 1 kcal per 100 g. 6 fl oz (178 g) is 2 kcal with 0.2 g of protein. Source: USDA FoodData Central record 171890, "Beverages, coffee, brewed, prepared with tap water".
How much protein is in black coffee?: Black coffee has 0.1 g of protein per 100 g and 0.2 g per 6 fl oz (178 g). That is 10 g of protein per 100 kcal — a solid protein-per-calorie ratio for a whole food.
Where do these calorie figures come from?: USDA FoodData Central record 171890, “Beverages, coffee, brewed, prepared with tap water” (SR Legacy, FDC SR Legacy 2018-04 + FNDDS 2024-10-31). Energy is USDA nutrient 1008 (Energy, kcal); protein, fat and carbohydrate are read from the same record. USDA data is in the public domain, and the FDC ID above links straight to it.

How calorie.one logs it

Type “black coffee” into calorie.one and the app matches this exact record — “Beverages, coffee, brewed, prepared with tap water” — estimates the grams, and shows the line with its USDA label. You correct the amount; the per-100 g figure is never guessed. That split between recognition and arithmetic is the whole methodology. For the numbers in context, read How accurate is calorie counting, really?.