A milligram is one-thousandth of a gram. If a label says 800 mg sodium, that is 0.8 g sodium—not 800 g. Keeping the unit beside the number prevents one of the largest possible comparison errors.
Work through the conversion
To move from milligrams to grams, divide by 1,000. To move from grams to milligrams, multiply by 1,000. An example sauce with 0.3 g sodium per portion therefore has 300 mg. Compared with an example soup containing 800 mg, the sauce has 500 mg less for those particular listed portions.
The food weight is another quantity
A 300 g bowl with 800 mg sodium contains a 300 g food portion and 0.8 g of the listed sodium. The two “300” values in the sauce and bowl examples do not mean anything alike. One is a nutrient amount in milligrams; the other is an entire food mass in grams.
Enter the calculator’s unit
The sodium tool asks for milligrams. Enter 300 for the example sauce, not 0.3. If your source uses grams, convert first and note that conversion. Check whether the nutrition is per portion or per 100 g before scaling; unit conversion alone does not fix a serving-size mismatch.
Finally, sodium and table salt are not interchangeable names. This guide converts sodium units only. It does not convert a salt figure into sodium or set a personal daily limit. NIST supports the mass-unit relationship, and FDA explains the distinction between sodium and salt. Both checks matter before a comparison can be trusted.
Sources and example boundaries
- NIST: units of mass
Gram, milligram and kilogram relationships.
- FDA: sodium
Sodium units and the distinction between sodium and salt.
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.