Use drained weight only with nutrition that describes the drained food. The can’s net weight and the weight of the solids you eat may be different. Neither number automatically tells you which basis the nutrition panel uses.
Read the serving-size line for wording such as “drained.” If it is unclear, check the manufacturer’s information. FDA’s Food Labeling Guide distinguishes packing liquid, drained weight and serving bases; it does not provide one conversion for every canned food.
One can, three useful numbers
| Number | What it describes | How to use it |
|---|---|---|
| Net contents | The contents declared on the package. | Do not assume all of it will be eaten. |
| Drained weight | The solids after the specified draining. | Use with a matching drained-food nutrition basis. |
| Serving weight | The amount the nutrition column describes. | Use as the denominator when scaling that column. |
A label that explicitly says drained
Imagine a can with 400 g net contents, 240 g drained solids, and a label listing 90 calories and 5 g protein per 80 g drained serving. These are sample numbers, not a real product.
If you eat 120 g of drained solids, the multiplier is 120 ÷ 80 = 1.5. That gives 135 calories and 7.5 g protein. Eating all 240 g would be three labeled servings: 270 calories and 15 g protein.
Using 400 ÷ 80 would incorrectly count five drained servings. The liquid is not part of the portion described in this example.
If the label describes food with liquid
You cannot turn an undrained nutrient value into a drained value merely by changing the weight. The discarded liquid and retained solids need not have the same nutrient concentration. Use a manufacturer’s drained value or a matching drained database food; identify it as a different source if you do.
Rinsing adds another preparation difference. Do not subtract a fixed sodium percentage unless the exact product and method have a supported value. A smaller scale reading does not prove a particular nutrient reduction.
Compare food labels after confirming that both labels describe the preparation you will eat.
Sources and scope
These sources support the factual explanations above. Worked label examples are illustrative where stated. Restaurant comparisons use the listed U.S. portions; availability and local recipes may differ.