Every part of an egg contains protein, but the white and the yolk contribute in different amounts. A large egg has about 6.3 grams of protein total: roughly 3.6 grams in the white and 2.7 grams in the yolk. That means the white holds about 57% of the egg’s protein, while the yolk carries the remaining 43%.
Protein in the Egg White
The egg white (also called the albumen) is mostly water and protein. It contains almost no fat and only about 17 calories per large egg. The dominant protein in egg white is ovalbumin, which makes up about 54% of all the white’s protein. The rest is a mix of other proteins that serve different biological roles, from fighting bacteria to binding vitamins.
Because the white is nearly pure protein with minimal fat or cholesterol, it became the go-to for people watching their calorie or fat intake. But gram for gram, you’re only getting slightly more than half the egg’s total protein when you eat the white alone.
Protein in the Egg Yolk
The yolk often gets overlooked as a protein source because people associate it mainly with fat and cholesterol. But with roughly 2.7 grams of protein per large egg, the yolk is a meaningful contributor. Its proteins are different from those in the white. Yolk proteins tend to be bound to fats and phosphorus, and they carry a wider range of nutrients along with them, including fat-soluble vitamins, lipids, and minerals.
The yolk also contains all nine essential amino acids, just like the white does. In fact, the yolk is richer in some amino acids relative to its size. It carries substantial amounts of lysine and threonine, both important for tissue repair and immune function. Discarding the yolk means losing not just those amino acids but also nutrients like choline, vitamin D, and iron that aren’t present in the white.
How the Amino Acids Compare
Both the white and the yolk supply all nine essential amino acids your body can’t make on its own. The white, being the larger portion, delivers higher absolute amounts of most of them. For a single large egg, the white provides about 335 mg of leucine (the amino acid most closely tied to muscle building) compared to 238 mg in the yolk. It also has roughly double the methionine and phenylalanine of the yolk.
The yolk holds its own in lysine (207 mg vs. 266 mg in the white) and threonine (117 mg vs. 148 mg). When you eat the whole egg, you get a complete, well-balanced amino acid profile. Whole egg protein scores a 118 on the PDCAAS scale (a standardized measure of protein quality, where 100 is considered perfect). That puts eggs on par with milk and well above beef, soy, and wheat.
Protein by Egg Size
The 6.3-gram figure applies to a standard large egg, which is what most recipes and nutrition labels reference. If you buy a different size, the protein content shifts accordingly:
- Small (38 g): 4.8 grams of protein
- Medium (44 g): 5.5 grams
- Large (50 g): 6.3 grams
- Extra large (56 g): 7.1 grams
- Jumbo (63 g): 7.9 grams
The ratio of white to yolk protein stays roughly the same across sizes, so the split is always close to 57/43 regardless of which carton you pick up.
Cooking Changes How Much Protein You Absorb
Raw eggs are less digestible than cooked ones. Research on egg protein digestibility found that raw eggs had a digestibility value of about 70%, while half-boiled eggs reached roughly 82% and hard-boiled eggs landed around 76%. Heat unfolds the proteins in a way that makes them easier for your digestive enzymes to break down. So while a raw egg and a cooked egg contain the same amount of protein on paper, your body extracts more from the cooked version.
This is worth knowing if you’re adding raw eggs to smoothies or shakes. You’re likely absorbing 10 to 12 percentage points less protein than you would from a cooked egg. Any cooking method, from scrambling to poaching, improves digestibility.
Whole Eggs vs. Egg Whites for Muscle
Earlier lab studies suggested that whole eggs stimulate muscle protein synthesis more effectively than egg whites in the hours after exercise, likely because fats and other yolk nutrients enhance the body’s protein-building signals. But longer-term research tells a more nuanced story. A 12-week study of resistance-trained men found that those eating whole eggs and those eating egg whites (matched for total protein) gained similar amounts of muscle mass and strength. The takeaway: as long as your overall protein intake is sufficient, choosing whites over whole eggs, or vice versa, doesn’t appear to make a significant difference for muscle growth over time.
For most people, eating the whole egg is the simplest way to get the full protein content along with the broader range of nutrients the yolk provides. If you’re specifically limiting calories or dietary fat, egg whites give you a concentrated, low-calorie protein source, just keep in mind you’re leaving about 43% of the egg’s protein behind.