How this calculator works
Micro and milli are SI prefixes: micro means one millionth and milli means one thousandth. A microgram is therefore one thousandth of a milligram, and it takes 1,000 micrograms to make one milligram. The symbol mcg is used in health care in place of µg because the Greek letter can be misread, but both spellings mean the same unit. This page only converts a stated mass from one unit to another. It does not check whether the amount is an appropriate dose.
Formula
milligrams = micrograms / 1,000. micrograms = milligrams x 1,000. grams = micrograms / 1,000,000. kilograms = micrograms / 1,000,000,000. pounds = kilograms / 0.45359237.
Worked example
1,000 mcg is 1 mg and 0.001 g. 2,500 mcg is 2.5 mg. 0.5 mg is 500 mcg. 1,000,000 mcg is 1 g. 1 lb is 453,592,370 mcg.
Advertisement
Frequently asked questions
Is mcg the same as µg?
Yes. Both are the microgram, one millionth of a gram. Health care settings often use mcg or µg rather than mg because mg is a thousand times larger and the two are easy to confuse in handwriting.
How many micrograms are in a milligram?
Exactly 1,000. The prefix micro is a factor of 10^-6 and milli is 10^-3, so the difference between them is 10^3, or one thousand.
Can I use this to check a medicine dose?
Only to convert a number from one unit to another. It cannot tell you whether a dose is correct. If a label or prescription seems to mix mcg and mg, ask a pharmacist or prescriber before taking or giving the medicine.
Why does the pound answer look so small or large?
A pound is about 453,592 milligrams, so a mass in micrograms divided into pounds is a very small number. The gram and kilogram rows are usually easier to read for everyday amounts.