Canned Tuna Calories and Protein: Water vs Oil and Can Size

Three ounces of drained canned light tuna contain about 99 calories and 22g protein when packed in water. The comparable drained tuna in oil is about 168 calories and 25g protein. The label on your particular can is the best number for that product.

How many calories and how much protein are in a can of tuna?

There is no single accurate “per can” figure. Cans come in different sizes, and the printed net weight includes water or oil that you may drain away. A nutrition label may also give values per serving when the can holds more than one serving. Read the serving size and servings per container first, then use the amount of tuna you ate.

For a practical reference, use the drained fish values below. They are calculated from University Hospitals' one-ounce entries and rounded to whole numbers. Your brand can differ by species, packing medium, salt and retained liquid.

Why oil-packed tuna differs

Oil-packed tuna retains more fat after draining, so it usually has more calories per ounce. Draining reduces the liquid you eat but does not turn oil-packed fish into water-packed fish. If you use the packing oil in a salad or pan, include it too. The protein numbers differ slightly across the reference products, but the dependable distinction is the extra fat and energy.

The 30-second label check

1. Find the serving size and number of servings per container.
2. Check whether the nutrition panel describes drained solids or the product as packaged.
3. Multiply by the servings you ate. If you use the oil or mix in mayonnaise, log those ingredients as well.

The FDA notes that nutrition facts are usually shown per serving, although some packages also show per package. A small can can still contain more than one labeled serving. For a sandwich, the bread and mayonnaise may add as much to the meal as the tuna itself. Our protein guide compares tuna with other everyday protein sources.

A note on eating tuna regularly

If tuna is a frequent meal, species matters for mercury exposure. The FDA lists canned light tuna among its “Best Choices” and canned albacore among its “Good Choices” in its fish advice, with different serving guidance for people who are or might become pregnant and for children. Follow that current guidance rather than using a calorie table to decide how often to eat it.

Frequently asked questions

How much protein is in a can of tuna?

It depends on how much drained fish the can contains. As a reference, 3 oz of drained canned light tuna in water has about 22g protein; 4 oz has about 29g.

Is tuna in water lower in calories than tuna in oil?

In the reference drained entries, yes. Three ounces of water-packed light tuna have about 99 calories, compared with about 168 for oil-packed tuna.

Should I use the can's net weight to log tuna?

Check the label first. Net weight may include packing liquid, while the amount of drained fish you eat can be lower.