Is peanut butter a good source of protein? Protein per serving, checked
Some foods have a reputation as "protein foods" that their numbers don't quite match. None of them is a bad food. The question is only how much protein a normal serving actually brings, and what else comes with it.
The numbers
Protein per common serving, from USDA FoodData Central:
| Food | Serving | Protein | Fat | Calories | Protein per 100 calories |
|---|---|---|---|---|---|
| Peanut butter | 2 tbsp (32 g) | 7.2 g | 16.4 g | 191 | 3.8 g |
| Almonds | 1 oz (28.35 g) | 6.0 g | 14.2 g | 164 | 3.7 g |
| Almond milk, unsweetened | 1 cup (262 g) | 1.0 g | 2.5 g | 39 | 2.6 g |
| Avocado | 1 cup cubes (150 g) | 3.0 g | 22.0 g | 240 | 1.3 g |
| Quinoa, cooked | 1 cup (185 g) | 8.1 g | 3.6 g | 222 | 3.6 g |
| Egg, hard-boiled | 1 large (50 g) | 6.3 g | 5.3 g | 78 | 8.1 g |
| Lentils, cooked | 1 cup (198 g) | 17.9 g | 0.8 g | 230 | 7.8 g |
| Edamame, cooked | 1 cup (180 g) | 22.2 g | 11.5 g | 254 | 8.7 g |
| Tofu, firm | 1/2 cup (126 g) | 21.8 g | 11.0 g | 181 | 12.0 g |
| Cottage cheese, 2% | 1 cup (226 g) | 23.6 g | 5.1 g | 183 | 12.9 g |
| Canned light tuna, in water | 3 oz (85 g) | 21.7 g | 0.7 g | 99 | 21.9 g |
| Chicken breast, roasted | 1/2 breast (86 g) | 26.7 g | 3.1 g | 142 | 18.8 g |
Values are USDA FoodData Central entries for the foods as named, scaled to the serving shown.
What the numbers say
- Peanut butter is mostly fat. Two tablespoons bring about 7 g of protein and about 16 g of fat. It's a good food with some protein in it. Per calorie it brings about 4 g of protein per 100 calories, against about 19 g for chicken breast.
- Almond milk is not a milk substitute for protein. A cup of unsweetened almond milk has about 1 g of protein; a cup of cow's milk has about 8 g. Soy milk is the plant milk that comes close.
- Avocado brings fiber and fat, not much protein. Its strength is about 10 g of fiber per cup.
- Quinoa is a complete protein, but not a large one. A cup of cooked quinoa has about 8 g of protein, about the same as a cup of milk. That's more than rice, and less than a cup of lentils.
- One egg is about 6 g. Eggs are high-quality protein, but you need about four to match a portion of chicken or tofu.
Per serving, not per 100 grams
Many "high in protein" lists rank foods per 100 g. That makes nuts, seeds and peanut butter look like top protein sources, because they are dense and dry. Nobody eats 100 g of peanut butter at once. Per normal serving, the order changes.
More protein is not the same as a good protein source
Whether a food is a good source of protein is about how much protein you get for the calories, not how many grams a serving has. A common rule of thumb: multiply the grams of protein by 10, and if that's at least the calories, at least about 40% of the calories come from protein (protein has 4 calories per gram). Two tablespoons of peanut butter: 7 × 10 = 70, against 191 calories. A roasted half chicken breast: 27 × 10 = 270, against 142 calories.
By that rule, chicken, tuna, cottage cheese and tofu qualify; lentils, edamame and eggs bring plenty of protein but come in just under, because they bring carbs or fat too. Neither group is better food. It depends on whether you're filling a protein target within a calorie budget, or just eating.
How much protein do you need?
The Recommended Dietary Allowance (RDA) for adults is 0.8 g per kg of body weight a day. People who train regularly often aim higher; sports-nutrition position stands put the range at roughly 1.2 to 2.0 g per kg. The free macro calculator gives you a starting target from your own details and shows the sources it uses.
Check your own
In Speed Macros, type the food the way you'd say it, for example "2 tbsp peanut butter", and the entry shows protein, carbs, fat and fiber, marked "USDA data" when it matches USDA's table. The calorie and macro tracker adds your day up. For foods that bring protein and fiber together, see high-protein, high-fiber foods.
This guide is general information, not medical advice. If you have kidney disease or another reason to limit protein, follow your clinician's advice.
Sources: USDA FoodData Central (entries 1100559, 170567, 174832, 171705, 168917, 173424, 172421, 169283, 172475, 172182, 171986, 171477; cow's milk from 171265) · National Academies, Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids, 2005 (protein RDA 0.8 g/kg) · Thomas DT, Erdman KA, Burke LM. "American College of Sports Medicine Joint Position Statement: Nutrition and Athletic Performance." Med Sci Sports Exerc. 2016;48(3):543–568