A milligram and a microgram are different amounts. One milligram is 1,000 micrograms. If you copy a nutrient value into a table without its unit, a harmless-looking decimal can become a thousand-fold recording error.
Keep the prefix with the number
An invented label listing 20 micrograms records 0.020 milligrams, not 20 milligrams. Conversely, 2 milligrams is 2,000 micrograms. The arithmetic converts the unit; it does not change the amount of the nutrient in the food.
Different nutrients need different units
Protein is commonly shown in grams, sodium in milligrams and some vitamins in micrograms. Adding or comparing the raw numbers without identifying the nutrient and unit is meaningless. Twenty micrograms of one vitamin is not automatically more or less useful than 2 milligrams of another.
Daily Values are another field
A unit conversion is not a Daily Value calculation. To calculate a percentage, you need the reference amount for that exact nutrient in the same unit. Do not use a sodium denominator for a vitamin or guess a vitamin target from the size of its number.
A simple recording check
Write the nutrient name, numeric amount, unit and serving together. When converting, show the original and converted amount side by side, then verify that multiplying back returns the starting value. NIST supports the metric-prefix relationships and FDA supports label serving context. The examples here introduce no supplement dose, medical advice or personal nutrient target.
Sources and example boundaries
- NIST: metric prefixes
Milli and micro represent powers of ten; supports the conversion between milligrams and micrograms.
- 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.