Mg to Mcg Converter

How to convert mg to mcg

1. Take the number in milligrams.
2. Multiply it by 1,000. That moves the decimal point three places to the right.
3. Write the unit as mcg.

A worked example: 0.75 mg × 1,000 = 750 mcg. To go back, you divide by 1,000 instead. The mcg to mg converter does that side for you, with a table that starts from micrograms.

When the number runs out of digits, add zeros as you move the point. That is why 0.3 mg turns into 300 mcg and not 3 mcg.

Mg, mcg and g at a glance

1 g = 1,000 mg = 1,000,000 mcg. The prefix "milli" means one thousandth. The prefix "micro" means one millionth. Both come from the metric system, and the US measurement lab, NIST, lists them in its table of SI prefixes.

So a microgram is a thousand times smaller than a milligram. A milligram is a thousand times smaller than a gram. For the bigger step, see mg to g.

Same number, different unit

5 mcg and 5 mg are not the same. 5 mg is 1,000 times more. Always read the unit, not just the number.

This mix up is easy to make, because the two units look alike. A label may also show the micro sign (µg) in place of mcg. The mg vs mcg guide puts the two side by side, and what is mcg explains each way of writing it.

Write numbers so they cannot be misread

A US safety group, the Institute for Safe Medication Practices (ISMP), keeps a list of ways of writing numbers that cause mix ups. Three of its rules help with mg and mcg:

• Put a zero before the point: 0.5 mg, not .5 mg. If the point is missed, .5 can look like 5.
• Leave off a zero after the point: 1 mg, not 1.0 mg. If the point is missed, 1.0 can look like 10.
• Write mcg, not µg. A handwritten µ can look like an m, so µg can be read as mg.

The converter above checks for the first two. Type .5 or 5.0 and it shows a note.