Why “Per 100g” Is the Only Fair Comparison
Nutrition labels use serving sizes that vary wildly — a “serving” of milk is 240ml, a serving of almonds is 28g, a serving of chicken is 85g. Comparing them directly is meaningless. USDA FoodData Central publishes everything per 100g of edible portion, which is the only basis on which beef, beans, and bread can be lined up honestly.
The FDA Daily Value for protein is 50g per day on a 2,000-calorie diet. Most adults need more than that if they are active — commonly cited targets run from 0.8g to 1.6g per kilogram of body weight per day.
The Full Comparison: Protein Per 100g
All values are per 100g of edible portion. Cooked weights are used where a food is normally eaten cooked.
Source: USDA FoodData Central. Values are per 100g edible portion.
🥩 See the full protein ranking across all foods →The Dry vs. Cooked Trap
This is where most “protein per 100g” comparisons go wrong. Dry beans, grains, and pasta absorb water during cooking — roughly tripling in weight. USDA lists both states, and the numbers look completely different:
| Food (FDC ID) | Protein (g) | Calories (kcal) | Fat (g) |
|---|---|---|---|
| Beans, black — cooked, boiled(173735) | 8.9 | 132 | 0.5 |
| Beans, black — raw (dry)(173734) | 21.6 | 341 | 1.4 |
| Lentils — cooked, boiled(172421) | 9.0 | 116 | 0.4 |
| Lentils — raw (dry)(172420) | 24.6 | 352 | 1.1 |
| Mung beans — cooked, boiled(174257) | 7.0 | 105 | 0.4 |
| Mung beans — raw (dry)(174256) | 23.9 | 347 | 1.2 |
A headline like “lentils have 25g of protein per 100g” is technically true but refers to dry lentils, which nobody eats. Once cooked, the same lentils deliver 9.0g per 100g. Both numbers are correct — they just describe different things. Always check whether a legume figure is the raw or the cooked entry.
Animal vs. Plant Protein: What the Numbers Show
🍗 Animal Sources
Typically 20–31g per 100g cooked
Complete amino acid profiles and high digestibility. The main variable is fat: chicken breast is 3.6g fat per 100g, while farmed salmon is 12.4g.
🌱 Plant Sources
Typically 7–18g per 100g cooked
Lower per 100g, but they arrive with fiber that animal foods lack entirely — cooked black beans carry 8.7g of fiber per 100g against 0g in any cut of meat.
Soybeans are the exception that proves the rule: at 18.2g per 100g cooked, they land in animal-protein territory and provide a complete amino acid profile. Most other legumes are limited in methionine, and grains are limited in lysine — which is why the classic beans-and-rice pairing found in nearly every cuisine works nutritionally.
Per 100g vs. Per Realistic Portion
Per-100g rankings favor dense, dry foods. Ranking by what you actually eat in one sitting changes the order considerably:
| Food | Typical portion | Protein (g) |
|---|---|---|
| Chicken breast, roasted | 4 oz / 113g | ~35 |
| Beef, ground 93% lean, cooked | 4 oz / 113g | ~33 |
| Salmon fillet, cooked | 5 oz / 142g | ~31 |
| Canned tuna, drained | 1 can / 142g | ~36 |
| Greek yogurt, plain lowfat | 1 cup / 227g | ~23 |
| Black beans, cooked | 1 cup / 172g | ~15 |
| Lentils, cooked | 1 cup / 198g | ~18 |
| Milk, whole | 1 cup / 244ml | ~8 |
| Whole-wheat bread | 2 slices / 56g | ~7 |
| Almonds | 1 oz / 28g | ~6 |
Portion protein calculated from the per-100g USDA values above. Notice that whole milk — near the bottom per 100g at 3.2g — still delivers about 8g per cup, because a cup is a large portion.
Key Takeaways
- ✓Cooked animal protein clusters at 20–31g per 100g; cooked legumes at 7–18g; cooked grains at 3–5g.
- ✓Chicken breast (31.0g) leads the common foods, with pork tenderloin (30.4g) and lean ground beef (28.9g) close behind.
- ✓Always check whether a legume figure is dry or cooked — dry lentils show 24.6g, cooked lentils 9.0g.
- ✓Whole milk is only 3.2g per 100g but around 8g per cup; per-100g rankings penalize watery foods.
- ✓Soybeans (18.2g cooked) are the only common legume that matches animal sources on both quantity and amino acid completeness.
- ✓Plant sources bring fiber that animal sources have none of — cooked black beans supply 8.7g per 100g.
Related reading: Protein-Rich Foods, Beans and Legumes Nutrition, and Milk vs Greek Yogurt vs Cheese.
Data Source
・USDA FoodData Central — Foundation Foods and SR Legacy
・FDA Daily Values (21 CFR 101.9)
This article is general nutrition information and is not intended to diagnose or treat any condition.