Convert milligrams to micrograms
Type a value in milligrams and read the result in micrograms. One milligram is a thousand micrograms, so 0.5 mg gives 500 mcg. The result updates as you type, and the page also lists fractions of a milligram, the µg, mcg, ug and γ notations and rules for writing the result.
How many micrograms are in a given number of milligrams?
Multiply the number of milligrams by 1,000 to get micrograms. Half a milligram, written 0.5 mg, comes out as 500 mcg.
Formula: micrograms = milligrams × 1,000
By hand, move the decimal point three places to the right. This turns 0.025 mg into 25 mcg. It also turns 0.1 mg into 100 mcg. Missing places are filled with zeros, so 2 mg gives 2,000 mcg.
The factor is exact because milli and micro are powers of ten in the SI. Milli means 10⁻³ and micro means 10⁻⁶[1]. A gap of three orders of magnitude is exactly a thousand.
The converter multiplies by 1,000 as you type and shows the result to three decimal places. Even a millionth of a milligram, 0.000001 mg, therefore appears in the field as 0.001 mcg. The Copy result button places the number on the clipboard.
To convert micrograms to milligrams, use the micrograms to milligrams converter. Larger masses in grams come from the milligrams to grams converter.
What is a milligram, and what is a microgram?
A milligram is one thousandth of a gram. A microgram is a thousand times smaller, so one milligram is made up of 1,000 micrograms.
The SI symbol for the microgram is µg, because the micro prefix is written with the Greek letter μ[1]. The same unit is also written mcg. The English Wikipedia article on the microgram describes mcg as the preferred abbreviation for medical information in the United States[2].
UK prescription-writing guidance sets another rule. The NHS Scotland guide for dental prescribers, which points to the British National Formulary (BNF) for further advice, allows milligrams to be shortened to mg, while micrograms and nanograms must be written in full[3].
How many mcg are 0.1 mg, 0.5 mg and 1 mg?
| Milligrams | Micrograms | Grams |
|---|---|---|
| 0.001 mg | 1 mcg | 0.000001 g |
| 0.002 mg | 2 mcg | 0.000002 g |
| 0.0025 mg | 2.5 mcg | 0.0000025 g |
| 0.005 mg | 5 mcg | 0.000005 g |
| 0.01 mg | 10 mcg | 0.00001 g |
| 0.0125 mg | 12.5 mcg | 0.0000125 g |
| 0.015 mg | 15 mcg | 0.000015 g |
| 0.02 mg | 20 mcg | 0.00002 g |
| 0.025 mg | 25 mcg | 0.000025 g |
| 0.03 mg | 30 mcg | 0.00003 g |
| 0.04 mg | 40 mcg | 0.00004 g |
| 0.05 mg | 50 mcg | 0.00005 g |
| 0.06 mg | 60 mcg | 0.00006 g |
| 0.075 mg | 75 mcg | 0.000075 g |
| 0.08 mg | 80 mcg | 0.00008 g |
| 0.1 mg | 100 mcg | 0.0001 g |
| 0.125 mg | 125 mcg | 0.000125 g |
| 0.15 mg | 150 mcg | 0.00015 g |
| 0.175 mg | 175 mcg | 0.000175 g |
| 0.2 mg | 200 mcg | 0.0002 g |
| 0.25 mg | 250 mcg | 0.00025 g |
| 0.3 mg | 300 mcg | 0.0003 g |
| 0.35 mg | 350 mcg | 0.00035 g |
| 0.4 mg | 400 mcg | 0.0004 g |
| 0.5 mg | 500 mcg | 0.0005 g |
| 0.6 mg | 600 mcg | 0.0006 g |
| 0.75 mg | 750 mcg | 0.00075 g |
| 0.8 mg | 800 mcg | 0.0008 g |
| 0.9 mg | 900 mcg | 0.0009 g |
| 1 mg | 1,000 mcg | 0.001 g |
| 1.2 mg | 1,200 mcg | 0.0012 g |
| 1.5 mg | 1,500 mcg | 0.0015 g |
| 2 mg | 2,000 mcg | 0.002 g |
| 2.5 mg | 2,500 mcg | 0.0025 g |
| 3 mg | 3,000 mcg | 0.003 g |
| 4 mg | 4,000 mcg | 0.004 g |
| 5 mg | 5,000 mcg | 0.005 g |
| 7.5 mg | 7,500 mcg | 0.0075 g |
| 10 mg | 10,000 mcg | 0.01 g |
| 12.5 mg | 12,500 mcg | 0.0125 g |
| 15 mg | 15,000 mcg | 0.015 g |
| 20 mg | 20,000 mcg | 0.02 g |
| 25 mg | 25,000 mcg | 0.025 g |
| 50 mg | 50,000 mcg | 0.05 g |
| 100 mg | 100,000 mcg | 0.1 g |
How do µg, mcg, ug and γ differ?
| Notation | Where it is used | 0.5 mg written this way |
|---|---|---|
| µg | The SI symbol for the unit | 500 µg |
| mcg | Medical information in the United States, recommended by ISMP | 500 mcg |
| ug | The microgram code in the Excel CONVERT function | 500 ug |
| γ (gamma) | An older notation that is no longer recommended | 500 γ |
| micrograms | The word written in full on UK prescriptions | 500 micrograms |
Which number formats does this converter handle?
| What you type | What the converter shows | How we read it |
|---|---|---|
| 0.5 | 500 mcg | The decimal point from the numeric keypad, written the way English writes it |
| 0,5 | 500 mcg | A comma pasted from a market that writes decimals that way is read as a decimal point, so the result is the same |
| 1,500 | 1500000 mcg | Three digits follow the comma, so we read it as a thousands separator: the field holds one thousand five hundred. A note under the field shows the other possible reading, 1.5. |
| 3/4 | 750 mcg | We work the fraction out ourselves, so there is no need to turn it into a decimal first |
| 2½ | 2500 mcg | The ½ character copied from a recipe or a label is added to the number in front of it |
| 0.5 mg | 500 mcg | A unit symbol pasted along with the number is no trouble: we take the number and leave the symbol out |
How do you write a result in mg or mcg so that it is read correctly?
When you copy a result from the converter onto paper or into a document, the way it is written matters too. The ISMP list sets out how doses should be written in medical information, including where zeros go around the decimal point[4].
Put a zero before the decimal point
Write a value below one milligram as 0.5 mg. The ISMP list recommends a leading zero for every dose below one measurement unit[4].Write whole numbers without a trailing zero
Write one milligram as 1 mg. For doses expressed in whole numbers, the same list recommends leaving out the trailing zero[4].Switch to micrograms for small fractions of a milligram
A mass of 0.025 mg is 25 mcg, and the second form has fewer digits to read. In the same way, 0.0025 mg can be written more briefly as 2.5 mcg.Match the notation to the reader
For a reader in the United States, use mcg. On a UK prescription, write micrograms in full.
Convert other units to Micrograms
Convert Milligrams to other units
Sources
- Metric (SI) Prefixes — National Institute of Standards and Technology
- Microgram — Wikipedia
- Guide to Prescription Writing — Scottish Dental Clinical Effectiveness Programme (NHS Scotland)
- ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations — Institute for Safe Medication Practices
- CONVERT function — Microsoft
Every figure in the tables was computed from the unit definitions and checked arithmetically before publication. Historical values and the names of local units come from the sources listed above.
Content last reviewed: · written and checked by the Arteon team
Common questions about converting milligrams to micrograms
How many mcg is 1 mg?
One milligram is 1,000 mcg, which is also 1,000 µg, because both abbreviations name the microgram.
Is 0.1 mg the same as 100 mcg?
Yes. Multiplying 0.1 by 1,000 gives 100, and mcg is another way of writing the microgram.
Do µg and mg differ in letter case?
No. Both prefixes denote submultiples, and those are written in lower case[1]. The letter m stands for milli and the Greek letter μ stands for micro. Capital M belongs to the prefix mega, which means a million.
How do I convert mg to mcg in Excel?
Multiply the cell by 1,000, for example =A1*1000. The CONVERT function writes the same thing as =CONVERT(A1,"mg","ug"), because it uses the letter “u” for the micro prefix[5].
Can I type a quarter of a milligram as 1/4?
Yes. A quarter of a milligram can be typed as 0.25 or as 1/4. The result in micrograms appears as you type.
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