Check a whole-package column without mixing its serving numbers
Use a three-serving consistency table to check package totals, preserve the printed values, and investigate mismatches.
A bag can have one nutrition column for a serving and another for everything inside. Before multiplying any numbers, decide which column already answers your question. Multiplying a whole-package value by the serving count would count the same food several times.
The FDA serving-size explanation describes both serving and package columns. The worksheet below is an original arithmetic exercise using hypothetical crackers, not a test of a manufacturer's label.
Make a three-serving check table
Imagine a 90 g bag with a 30 g stated serving and exactly three servings in this example. Copy each column separately before doing the check. Keep grams and milligrams attached to every nutrient.
| Item | Per serving | Calculated package | Printed package |
|---|---|---|---|
| Food weight | 30 g | 30 × 3 = 90 g | 90 g |
| Protein | 4 g | 4 × 3 = 12 g | 12 g |
| Sodium | 180 mg | 180 × 3 = 540 mg | 540 mg |
The example is internally consistent at the precision displayed. A second check gives the same concentration from either column: 180 ÷ 30 × 100 and 540 ÷ 90 × 100 both produce 600 mg sodium per 100 g. This equality helps catch accidentally crossed columns.
Separate the amount eaten from the amount bought
If you eat 60 g, you have eaten two of these stated servings. The estimate is 8 g protein and 360 mg sodium, not the package totals. If you finish the bag, use the package column directly. Buying one bag does not establish which of these amounts you consumed.
A saved comparison should include four fields: the label heading, food quantity, nutrient quantity, and unit. A value such as “540” detached from its package heading is easy to reuse incorrectly in another worksheet.
Investigate a discrepancy without rewriting the label
On a real label, an approximate serving count or rounded nutrient declarations can prevent a perfect multiplication match. Preserve both printed figures. Recheck whether a column describes preparation, an individual unit, or the entire package before treating a difference as an error.
This check tests the consistency of your transcription. It cannot establish the exact nutrient content of a particular bag, prove regulatory compliance, or replace clarification from the manufacturer when the headings remain ambiguous.