A standard 5-ounce can of tuna provides about 26 grams of protein, making it one of the most protein-dense foods available. The exact amount varies depending on the type of tuna and how it’s packed, but even a smaller 3-ounce serving delivers 16 to 21 grams.
Protein by Type of Tuna
Not all tuna is created equal when it comes to protein. Fresh tuna has a slight edge over canned because the heat used during canning reduces protein content somewhat. Here’s how the main varieties compare in a 3-ounce serving:
- Fresh yellowfin (ahi): about 21 grams of protein per 3 ounces raw, with very little fat
- Fresh bluefin: about 23 grams per 100 grams (roughly 3.5 ounces), with more fat than other varieties. NOAA describes bluefin as the darkest and fattiest tuna, and that higher fat content is considered a mark of quality.
- Canned white albacore (in water): 26 grams in a full 5-ounce can, or about 19 grams per 3-ounce portion
- Canned light/skipjack: roughly 13 grams per 2-ounce serving, scaling to about 16 to 20 grams for a 3-ounce portion
If you’re buying canned tuna specifically for protein, white albacore in water tends to pack the most per can. Light tuna (usually skipjack) is slightly lower in protein but still an excellent source.
Water-Packed vs. Oil-Packed
The packing liquid doesn’t meaningfully change the protein content. Both water-packed and oil-packed canned tuna deliver 16 to 20 grams of protein per 3-ounce serving. The real difference is in fat and omega-3s. When tuna sits in oil, its beneficial omega-3 fatty acids migrate into the surrounding liquid. Draining the oil means draining some of those omega-3s along with it. Water-packed tuna retains more of its original omega-3 content and has fewer total calories, which is why it’s the go-to for people focused on lean protein.
Why Tuna Protein Is High Quality
Tuna is a complete protein, meaning it contains all nine essential amino acids your body can’t make on its own. It’s particularly rich in leucine, the amino acid most directly involved in triggering muscle repair and growth. A 3-ounce serving of cooked skipjack tuna contains about 1.9 grams of leucine, and canned white tuna in oil has about 1.8 grams. For context, most adults need around 2 to 3 grams of leucine per meal to maximally stimulate muscle building, so a single can of tuna gets you most of the way there.
Tuna also has zero carbohydrates, which makes it useful for people tracking macros or following low-carb diets. A 5-ounce can of albacore in water is essentially pure protein with a small amount of fat.
How Much Tuna You Can Safely Eat
Mercury is the main reason you can’t just eat tuna at every meal. Different types carry different amounts, and the FDA groups them into distinct safety categories.
Canned light tuna (skipjack) falls in the “Best Choices” category, meaning you can safely eat 2 to 3 servings per week. Albacore contains about three times more mercury than light tuna, so the FDA places it in the “Good Choices” category: limit it to 1 serving per week, and don’t eat other fish that week. Bigeye tuna, sometimes sold as ahi in restaurants, is in the “Choices to Avoid” category entirely. A standard adult serving is 4 ounces, measured before cooking.
These guidelines are designed with pregnant women and young children in mind, but they’re a reasonable ceiling for anyone. If you’re relying on tuna as a daily protein source, stick with light tuna and rotate in other lean proteins to stay well under mercury limits.
Quick Protein Counts at a Glance
- 1 oz fresh yellowfin: ~7 g protein
- 3 oz fresh tuna (any variety): 20 to 21 g protein
- 3 oz canned tuna (any packing liquid): 16 to 20 g protein
- 5 oz can albacore in water: 26 g protein
- 6 oz fresh yellowfin: ~41 g protein
A single 5-ounce can covers roughly half the daily protein needs for a 140-pound adult, at a cost of about 150 to 200 calories depending on the variety and packing method. Few other shelf-stable foods come close to that protein-to-calorie ratio.