Do not add the % Daily Value column from top to bottom. Sodium, fiber and other nutrients use different reference amounts. Their percentages describe separate comparisons, not slices of one nutrition pie.
Three percentages, three questions
Suppose an example portion shows 10% DV sodium, 20% DV fiber and 15% DV calcium. Adding them gives 45%, but that does not mean the meal covers 45% of your nutrition needs. The sodium percentage asks how the sodium amount compares with its reference. Fiber and calcium use their own denominators.
Portion changes do not join the categories
Eating two identical portions would approximately double each displayed amount before rounding: 20% sodium, 40% fiber and 30% calcium in this example. These still remain three separate statements. There is no meaningful 90% total across them.
Use the column horizontally
The practical comparison is the same nutrient across foods. Put sodium beside sodium for equivalent portions, or fiber beside fiber. A percentage can make unlike nutrient units easier to interpret, but it does not turn an entire label into one score. If you are following a personal target from a clinician, that target may differ from the label reference.
When entering a calculator, use the nutrient amount in its stated unit, such as grams or milligrams. Never enter “20” from a percentage field into a grams field merely because the numbers look similar. The FDA Daily Value guide explains the reference system; the arithmetic above is an original example of why summing the column loses the meaning of each line.
Sources and example boundaries
- FDA: Daily Values
Percent Daily Value is a reference comparison, not a personalised target.
All food figures and prices in the worked example are invented to explain the method. They are not restaurant nutrition, tested recipes, shopping prices or personal dietary advice. Use the current label for the product you actually have.