The calories in 100g of tuna depend on the type of tuna and how it was packed or cooked. Raw tuna, drained canned tuna, and oil-packed tuna can all land in different calorie ranges.
If you want an accurate number, the best approach is to identify the exact product, weigh the edible portion, and use the label or a trusted nutrition database. That keeps your calorie count consistent and much more reliable than guessing.
1) Identify the kind of tuna first
Start by separating tuna into the version you actually ate: raw, canned in water, canned in oil, or a prepared tuna salad. This matters because 100g of tuna is not one fixed number. A plain, lean tuna steak is usually lower in calories than tuna packed in oil or mixed with mayonnaise.
As a practical rule, 100g of tuna is often around 100 to 120 calories when it is plain or packed in water, while oil-packed versions can be notably higher. If you are trying to track calories closely, use the exact entry for the species and preparation.
2) Weigh the right portion
Use a kitchen scale and weigh the part you actually eat. For canned tuna, that usually means the drained fish, not the whole can with liquid. For fresh tuna, weigh it raw if you are logging raw nutrition data, or cooked if your app or database lists cooked values.
This step prevents the biggest tracking error: using the can weight or package weight instead of the edible tuna. If you are also tracking training, Fitnit can help keep your workout log accurate with automatic rep counting and form feedback, which makes it easier to stay consistent while you dial in food intake.
3) Check the label or database entry
For the most accurate number, read the Nutrition Facts label first. Then compare it with a trusted database such as USDA FoodData Central if the package is missing details or you are using fresh tuna.
Look for calories per serving, serving size in grams, and whether the calories are listed for drained tuna, raw fish, or tuna mixed with other ingredients. If the serving size is different from 100g, convert it before logging.
4) Adjust for oil, sauces, and recipe add-ins
Plain tuna is easy to estimate. Tuna salad, tuna pasta, and tuna melts are not, because mayonnaise, oil, cheese, bread, and sauces can add a lot of calories fast. If the tuna was cooked in oil or mixed with dressing, count those ingredients separately.
A good habit is to log each ingredient by weight. That gives you a much better estimate than entering only “tuna” and hoping the app fills in the rest.
5) Watch for the most common mistakes
Do not assume every tuna product has the same calories. Skip the guesswork on species, packing liquid, and drained weight. Also avoid mixing raw and cooked entries, since cooking changes water content and can change the calorie value per 100g of the food you weigh.
If your goal is fat loss, the calorie number is only one part of the picture. Tuna is also a high-protein food, so it can be helpful for satiety and meal planning, but the total calories still depend on how it is prepared.
Sources
- USDA FoodData Central — USDA
- Mayo Clinic: Counting calories — Mayo Clinic
Frequently Asked Questions
How many calories are in 100g of tuna?
Usually about 100 to 120 calories for plain tuna or tuna packed in water, but oil-packed tuna can be higher.
Is canned tuna lower in calories than fresh tuna?
Not always. Canned tuna in water is often similar to fresh tuna, while oil-packed tuna is usually higher.
Should I count tuna drained or undrained?
Count the drained tuna if that is what you eat. The packing liquid is not part of the fish itself.
Why do calorie numbers for tuna vary so much?
Species, fat content, packing liquid, and whether the tuna is raw or cooked all change the calorie count.
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