Sodium and salt on food labels: convert before comparing
Convert milligrams of sodium to grams of salt equivalent, align serving sizes, and avoid a common imported-food comparison error.
A sodium number in milligrams and a salt number in grams cannot be compared directly. There are two separate tasks: convert sodium to salt equivalent, and put both products on the same food-weight basis. Do both before deciding which number is larger.
The EU labelling definition uses salt equivalent = sodium × 2.5. This is a label conversion, not a measurement of how much table salt someone added to a recipe. See Annex I of Regulation (EU) No 1169/2011, consolidated text. EU nutrition declarations express quantities per 100 g or 100 ml. European Commission guidance.
Start by writing the units
For a hypothetical soup, product A lists 360 mg sodium per 240 g serving. Convert the sodium to grams first: 360 ÷ 1,000 = 0.36 g sodium. Then multiply by 2.5: 0.36 × 2.5 = 0.90 g salt equivalent for that serving.
Now convert the serving to 100 g: 0.90 ÷ 240 × 100 = 0.375 g salt equivalent per 100 g. Suppose product B directly lists 0.40 g salt per 100 g. The values to compare are 0.375 and 0.40, not 360 and 0.40. These are illustrative numbers, not claims about products on sale.
Use the reverse calculation as a check
For product B, salt divided by 2.5 gives sodium in the same unit: 0.40 ÷ 2.5 = 0.16 g sodium per 100 g. Multiplying by 1,000 gives 160 mg sodium per 100 g. Product A provides 360 ÷ 240 × 100 = 150 mg sodium per 100 g. Both routes preserve the same ordering.
For a 300 g bowl, the calculations give 450 mg sodium for A and 480 mg sodium for B. That 30 mg difference belongs to this chosen portion and these inputs. It is not a conclusion about either product's overall suitability for a person's diet.
Keep the food state consistent
Check whether the panel refers to concentrated soup, soup prepared with water, or soup prepared with milk. A conversion of sodium to salt does not correct a mismatch between prepared and unprepared foods. Similarly, a value per 100 ml is not automatically a value per 100 g. Use supported weight or volume information rather than guessing density.
In the comparison tool, enter matching quantities: either sodium for both products or salt equivalent for both. Keep the same nutrient unit. Label a converted value as converted in your notes, retain the original printed value, and round only at the end so that later checks remain possible.