mcg to mg Converter
Converted amount
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Enter an amount and pick the two units.
- The factor between them
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The same amount in every unit
| Unit | Amount |
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How many mcg are in a mg?
A thousand. One milligram is 1000 micrograms, so 1000 mcg and 1 mg are the same amount of medicine written two different ways.
The prefixes carry the whole rule and never change: milli is a thousandth of a gram, micro is a millionth. That fixes every step on the ladder at a factor of 1000, which is why converting is a matter of moving the decimal point three places rather than looking anything up.
Unlike the mg to mL conversion, this one really is fixed. It holds for every drug, every product and every strength, because it is a relationship between units rather than a property of anything in the bottle.
How to convert mcg to mg
mg = mcg ÷ 1000 · mcg = mg × 1000
Dividing by a thousand moves the decimal three places left, so 500 mcg is 0.5 mg and 25 mcg is 0.025 mg. Multiplying moves it three places right, so 0.125 mg is 125 mcg.
Going up the ladder works the same way. A gram is 1000 mg, and a kilogram is 1000 g, so every step is the same factor and a two-step conversion is a factor of a million.
mcg to mg conversion chart
The amounts that come up most often, in both directions.
| Amount | Converts to |
|---|---|
| 1000 mcg | 1 mg |
| 500 mcg | 0.5 mg |
| 250 mcg | 0.25 mg |
| 100 mcg | 0.1 mg |
| 50 mcg | 0.05 mg |
| 25 mcg | 0.025 mg |
| 1 mg | 1000 mcg |
| 0.5 mg | 500 mcg |
| 0.25 mg | 250 mcg |
| 0.125 mg | 125 mcg |
Micrograms, milligrams, grams and kilograms
The whole ladder, showing what one of each unit is worth in the others.
| 1 of this | in mcg | in mg | in g | in kg |
|---|---|---|---|---|
| 1 mcg | 1 | 0.001 | 1e-6 | 1e-9 |
| 1 mg | 1000 | 1 | 0.001 | 1e-6 |
| 1 g | 1000000 | 1000 | 1 | 0.001 |
| 1 kg | 1000000000 | 1000000 | 1000 | 1 |
The same figures, along with the volume conversions, are collected on theconversion chart.
Why mcg is written out instead of µg
µg is the scientific symbol for a microgram, and it is the one you will see in a textbook. On a prescription it is a hazard, because a hurried handwritten µ reads as an m, which turns a microgram into a milligram and multiplies the dose by a thousand.
Medication safety guidance on both sides of the Atlantic therefore asks for microgram to be written in full, or abbreviated to mcg, and the same advice covers writing "unit" out rather than using U. This converter accepts µg, ug and mcg as the same unit, because all three turn up in real notes.
Once the units match, a dose in micrograms still has to meet a strength in milligrams before it becomes a volume, which is where the mg to mL calculator picks it up.
Questions about micrograms and milligrams
- How many mcg are in 1 mg?
- There are 1000 micrograms in a milligram. The prefixes are fixed: milli means a thousandth and micro means a millionth, so a milligram is a thousand times larger than a microgram.
- Is 1000 mcg the same as 1 mg?
- Yes. 1000 mcg and 1 mg are the same amount written two ways. Neither is stronger than the other.
- How do I convert mcg to mg?
- Divide by 1000. Going the other way, from mg to mcg, multiply by 1000. Dividing moves the decimal point three places to the left, so 500 mcg becomes 0.5 mg.
- What does mcg stand for, and why not µg?
- Both mean microgram. The symbol µg is the scientific form, but a handwritten µ can be misread as an m, which would multiply the dose by a thousand. Safety guidance in the UK and the US therefore asks for mcg to be written out on prescriptions instead.
- Which is bigger, mcg or mg?
- A milligram is bigger. One milligram equals 1000 micrograms, so a dose in mg is always the larger-sounding unit for the same quantity of medicine.