A unit of mass equal to one millionth of a gram. One milligram is equal to one thousand micrograms. It is also written on labels as mcg; confusing it with mg leads to a thousand-fold difference in the quantity reading.
Scale a thousand times smaller than a milligram
One milligram is equal to one thousand micrograms. The notation µg is sometimes replaced by mcg, especially in English-language materials. Changing the unit requires changing the number: 400 µg is 0.4 mg, not 400 mg. This is important when comparing vitamin and mineral labels. It is worth first reducing the values to one unit and then determining whether they refer to the same portion. A large number alone without a unit does not allow you to estimate the amount of a substance.
The decimal point and unit should remain visible when transcribing data. Losing the µ sign or changing mg to µg changes the scale a thousandfold. When comparing, it is helpful to write down the full unit name next to the conversion and double-check the value against the source label.
Meaning and application
A small sign next to a number can completely change the meaning of the declaration. A microgram is written, among others, as µg or mcg. Before comparing two products, check the unit because the numerical value alone does not convey the quantity without it.
In practice
Determine one working unit and recalculate both declarations before compilation. One milligram is equivalent to one thousand micrograms. Also keep a common base: capsule, tablet or full daily dose, exactly as stated on the label.
Do not use the conversion as a recommendation on how much you should take. IU cannot be converted into micrograms by one common conversion factor for all substances. If the writing is illegible, check the original label instead of guessing at the missing character.