A typical steak delivers roughly 25 to 29 grams of protein per 100 grams (about 3.5 ounces) of cooked meat, depending on the cut. A 4-ounce sirloin, for example, packs about 24 grams. That makes steak one of the most protein-dense whole foods available, and the cut you choose affects exactly how much you get.
Protein by Cut: Lean vs. Fatty
Not all steaks are created equal when it comes to protein. Leaner cuts consistently deliver more protein per serving because fat takes up less of the total weight. USDA data illustrates this clearly when you compare two ends of the spectrum per 100 grams of cooked beef:
- Eye of round (lean, trimmed): 29 g protein, 4 g fat, 154 calories
- Rib steak, small end (fattier, with 1/8″ fat): 25 g protein, 22 g fat, 304 calories
That’s a 4-gram protein difference per 100 grams, but the calorie gap is enormous. The rib cut carries nearly double the calories, almost entirely from fat. Sirloin, flank, and top round fall on the leaner side. Ribeye, porterhouse, and T-bone sit closer to the fattier end. If you’re eating steak primarily for protein, leaner cuts give you significantly more protein per calorie.
Why Cooking Changes the Numbers
This is where a lot of confusion starts. Nutrition labels on raw steak reflect the raw weight, but steak shrinks as it cooks because it loses water and some fat. A 6-ounce raw sirloin might weigh only about 4.5 to 5 ounces after cooking. The total protein doesn’t change, though. You still get the same grams of protein whether the steak is raw or cooked. What changes is the concentration: 100 grams of cooked steak has more protein than 100 grams of raw steak simply because the water is gone.
This also means doneness matters for weight, not nutrition. A rare steak retains more moisture and weighs more after cooking than the same steak cooked well done. The protein content is identical. If you’re tracking macros, the simplest approach is to weigh your steak raw and use the raw nutrition data.
Steak Protein Quality
Grams alone don’t tell the whole story. Protein quality depends on how well your body can digest and use the amino acids in a food. The current gold standard for measuring this is called the Digestible Indispensable Amino Acid Score, or DIAAS. Beef scores higher than plant-based protein sources on this measure. Research from the University of Illinois found that 93% lean beef burgers had significantly higher DIAAS values than plant-based alternatives like the Beyond Burger for both children and adults. For adults, 80% lean beef also scored higher than the Beyond Burger, though it was comparable to the Impossible Burger.
The practical takeaway: your body absorbs and uses a greater proportion of the protein in steak compared to most plant proteins. Beef contains all essential amino acids with no limiting amino acid for anyone over age 3, while some plant-based proteins fall short in sulfur-containing amino acids.
Leucine Content and Muscle Building
Leucine is the amino acid that acts as the primary trigger for muscle protein synthesis. Steak is one of the richest food sources. A standard 3-ounce serving of cooked steak provides roughly 1.8 to 2.4 grams of leucine depending on the cut. Top round delivers the most (about 2.4 g per 3 ounces), while tenderloin sits at the lower end (about 1.8 g). Sirloin and porterhouse land in between at around 1.9 to 2.0 grams.
Research suggests that about 36 grams of protein per meal, roughly equivalent to a 5- to 6-ounce cooked steak, aligns with evidence-based recommendations for maximizing muscle protein synthesis, particularly for older adults. That works out to about 0.45 grams of protein per kilogram of body weight per meal. Eating a steak larger than that in one sitting still provides usable protein, but the muscle-building signal doesn’t scale proportionally beyond that threshold.
Grass-Fed vs. Grain-Fed Protein
If you’ve wondered whether grass-fed steak has more protein, it doesn’t. According to Tufts University, grass-fed and grain-fed beef are very similar in nutrient content. The differences between the two show up primarily in fat composition (grass-fed tends to have slightly more omega-3 fatty acids and less total fat), not in protein quantity or quality. Choose whichever fits your budget and preferences without worrying about a protein gap.
Beyond Protein: What Else Steak Delivers
Steak is more than a protein source. A 4-ounce serving provides about 2.12 micrograms of vitamin B12, and three ounces of lean beef can cover your entire daily B12 requirement. Beef is also a meaningful source of iron (the heme form, which your body absorbs more efficiently than iron from plants), zinc, potassium, niacin, and folate. These nutrients work alongside the protein, which is part of why whole food protein sources tend to support health differently than isolated protein supplements.
Quick Reference by Serving Size
Here’s a rough guide for cooked steak, keeping in mind that leaner cuts sit at the higher end and fattier cuts at the lower end:
- 3 oz (85 g): 21 to 25 g protein
- 4 oz (113 g): 24 to 33 g protein
- 6 oz (170 g): 36 to 49 g protein
- 8 oz (227 g): 48 to 66 g protein
For context, most adults need somewhere between 50 and 130 grams of protein per day depending on body weight, activity level, and goals. A single 6-ounce steak covers a substantial share of that in one meal.