When you open a can of tuna, you probably don’t think much about how much fish is actually in there. But have you ever wondered just how much tuna you’re getting for your money? In this article, we’ll take a close look at canned tuna sizes, tuna can weights, and how to estimate the amount of tuna in a can.
Typical Canned Tuna Sizes
Canned tuna comes in a few common size varieties:
- 2.5 oz – A small can, good for a tuna salad sandwich
- 5 oz – A standard size can, enough for 2-3 sandwiches
- 6 oz – A slightly larger can, good for casseroles or salads
- 12 oz – A large restaurant-sized can, enough for multiple servings
The most popular sizes by far are the 5 oz and 6 oz cans. These provide a convenient single serving of tuna. The 2.5 oz cans are usually more expensive per ounce, but can be handy when you just need a little bit of tuna. The 12 oz size is more economical but requires multiple people to eat it before it goes bad.
Tuna Can Weight vs. Tuna Weight
It’s easy to assume that a 6 oz can of tuna contains 6 oz of fish. But in reality, a significant portion of the weight comes from the water and oil packing liquid inside the can.
According to the U.S. Food and Drug Administration (FDA), canned tuna is allowed to contain a minimum of 52% tuna by weight. The other 48% is made up of the packing liquid, as well as small amounts of other ingredients like salt, vegetable broth, or soybean oil.
This means that a 6 oz can of tuna likely only contains around 3 oz of actual tuna fish. The other 3 oz is packing liquid and other minor ingredients.
Drained vs Undrained Canned Tuna Weight
Canned tuna can be purchased in “drained” or “undrained” varieties. Drained tuna has some or all of the packing liquid removed before canning. Undrained tuna retains all of the original packing liquid.
A 6 oz can of undrained tuna contains about 3 oz of tuna and 3 oz of liquid. But a 6 oz can of drained tuna may contain up to 5 oz of tuna and only 1 oz of liquid. Check the product labels for more specifics.
Drained canned tuna is a better option if you want to maximize the amount of fish. It contains less liquid and more tuna flesh. Just be aware that the tuna may be dryer in texture without as much liquid.
Tuna Can Sizes and Approximate Tuna Weights
Based on the FDA guidelines and typical tuna can specifications, here are the approximate amounts of tuna in various size cans:
| Can Size | Total Can Weight | Approx. Tuna Weight |
|---|---|---|
| 2.5 oz | 2.5 oz | 1.3 oz |
| 5 oz (drained) | 5 oz | 3.5 oz |
| 5 oz (undrained) | 5 oz | 2.5 oz |
| 6 oz (drained) | 6 oz | 4.2 oz |
| 6 oz (undrained) | 6 oz | 3 oz |
| 12 oz (drained) | 12 oz | 8.4 oz |
| 12 oz (undrained) | 12 oz | 6 oz |
As you can see, drained cans contain significantly more tuna than undrained. But even for drained cans, the tuna content is around 20% less than the total can weight.
Calculating Tuna Protein from Canned Tuna
Many people eat canned tuna for the high-quality protein it provides. But how much protein is actually in a can of tuna?
On average, a 100g serving of canned tuna contains about 25g of protein. That means a 5oz (142g) can of tuna would contain approximately 35g of protein.
Here’s how to estimate the protein content of canned tuna:
- Check the can label for the approximate tuna content in ounces
- Multiply the tuna weight by 28.35 to convert ounces to grams
- Multiply the gram weight by 0.25 to estimate the grams of protein
- Divide the grams of protein by 28.35 to convert back to ounces
For example, a 5oz can of drained tuna contains approximately 3.5oz of tuna. Converting to grams:
- 3.5 oz tuna x 28.35 g/oz = 99.2 g tuna
- 99.2 g tuna x 0.25 protein factor = 24.8 g protein
- 24.8 g protein / 28.35 g/oz = 0.88 oz protein
So a typical 5oz can of drained tuna would provide around 0.88 ounces (25 grams) of protein per serving.
Mercury Levels in Canned Tuna
Canned tuna contains small amounts of mercury, a heavy metal that can be harmful in large doses. The FDA monitors mercury in seafood closely and provides guidelines for safe consumption.
Light tuna (“chunk light”) tends to be lower in mercury than white albacore tuna. According to FDA data, average mercury levels are:
- Chunk light tuna: 0.128 parts per million (ppm)
- White albacore tuna: 0.350 ppm
To stay below the EPA’s mercury reference dose of 0.1 micrograms per kg body weight, a 140 pound person could safely eat:
- Chunk light: 5 cans per week
- White albacore: 2 cans per week
Pregnant women and children have lower mercury limits and should consume no more than 1-2 cans per week.
Cost Comparison of Canned Tuna
Let’s take a look at the cost of canned tuna from a few popular brands:
| Brand | Can Size | Price | Price per Ounce |
|---|---|---|---|
| Kirkland chunk light | 12 oz | $1.34 | $0.11 |
| Bumble Bee solid white | 5 oz | $1.29 | $0.26 |
| Chicken of the Sea chunk light | 5 oz | $1.00 | $0.20 |
| StarKist chunk light | 5 oz | $0.99 | $0.20 |
| Wild Planet wild skipjack | 5.5 oz | $2.69 | $0.49 |
The 12 oz Kirkland brand offers the lowest cost per ounce at around 11 cents. Bumble Bee white albacore is the most expensive option at 26 cents per ounce. Wild Planet sustainable tuna is by far the priciest at nearly 50 cents per ounce.
For the best value, go with chunk light tuna cans larger than 5oz. Check your local stores for sales and coupons to save even more on canned tuna.
Tips for Getting the Most Tuna
Here are some tips to maximize the amount of tuna in canned tuna products:
- Choose drained or “solid pack” tuna to get more tuna and less liquid.
- Buy larger cans (12 oz) for a lower cost per ounce.
- Look for tuna packed in water instead of oil to reduce calorie intake.
- Get chunk light tuna for lower mercury levels than white albacore.
- Compare brands and buy on sale for the best price.
- Consider mixing flavors like herb-flavored for variety.
Conclusion
After looking at tuna can sizes, weights, drainage methods and more, we can draw some conclusions:
- The actual amount of tuna is around 20% less than the total can weight
- Drained canned tuna contains more tuna and less liquid
- Chunk light has less mercury than white albacore
- Bigger cans provide the lowest cost per ounce
Armed with the facts, you can choose the best canned tuna for your taste, budget and nutrition needs. Just be sure to mix up your protein sources and stick within the FDA’s mercury consumption guidelines.
