Compare a micronutrient without confusing mcg and mg
Convert micrograms and milligrams carefully, preserve nutrient identity, and avoid replacing a mass comparison with intake advice.
A tiny unit abbreviation can create a large numerical mistake. One milligram equals 1,000 micrograms. Micrograms may be written as mcg or with the symbol μg. Treat all of these abbreviations as part of the quantity, not as optional text to remove from a spreadsheet.
The FDA nutrient reference table uses both milligrams and micrograms. It provides context for the units; the invented values below are solely a comparison exercise and do not recommend a dose or supplement.
Start with a matched nutrient and portion
Suppose two fictional food records describe the same micronutrient per 100 g. Record A states 30 mcg. Record B states 0.045 mg. To compare in micrograms, multiply B by 1,000: 0.045 mg equals 45 mcg. B therefore has 15 mcg more per 100 g in this example.
To verify the result in milligrams, divide A by 1,000: 30 mcg becomes 0.030 mg. Subtracting 0.030 from 0.045 gives 0.015 mg, which is the same 15 mcg difference.
Add a portion only after fixing the unit
For a 60 g portion of A, the calculated amount is 30 × 0.60 = 18 mcg. For an 80 g portion of B, it is 45 × 0.80 = 36 mcg. These are different chosen portions, so their amounts answer a different question from the equal-weight comparison.
Keep a separate column for portion weight. Without it, someone reviewing the worksheet could incorrectly infer that B's concentration is twice A's. The concentration ratio is 45 ÷ 30 = 1.5; the selected portions produce the twofold amount difference.
Do not convert unfamiliar biological units by guessing
An IU declaration is not automatically interchangeable with mg or mcg through the same thousandfold rule. Likewise, a nutrient name followed by an equivalence term may require a nutrient-specific definition. If the two records use different forms or reporting conventions, stop and establish comparability first.
When exporting the comparison, write both the original and converted units in full at least once. Check decimal separators in imported records and avoid rounding a small milligram value to zero. This process compares reported quantities; it does not determine whether either product is appropriate for someone's medical needs.