Convert micrograms to kilograms
One microgram is 0.000000001 kg, so you divide the number of micrograms by one billion. Enter a mass in micrograms and the kilograms appear at once: 400 mcg gives 0.0000004 kg. The result also appears in scientific notation, and the Swap order button reverses the calculation.
The field also accepts scientific notation, for example 6.5e-7 or 6.5 × 10⁻⁷.
What is a microgram, and what is a kilogram?
A microgram takes its size from a prefix. The NIST table of SI prefixes gives the prefix micro the factor 10⁻⁶[1]. Combined with the gram, it forms the unit written as µg. That unit describes a mass one million times smaller than a gram.
At the other end of this scale is the kilogram, the SI base unit of mass[1]. NIST notes that its name already contains the prefix kilo, so further prefixes for mass attach to the gram[2].
The microgram and the kilogram are nine orders of magnitude apart. The Wikipedia entries on the microgram and the kilogram describe both units in more detail. The converter works this out with a single division, and the mcg to g converter covers the step through the gram.
How many kilograms is one microgram?
One microgram is 0.000000001 kg, one billionth of a kilogram. As a power of ten that is 10⁻⁹, so you divide the number of micrograms by one billion: kg = mcg ÷ 1,000,000,000.
The calculation consists of three identical steps. One thousand micrograms make a milligram. One thousand milligrams make a gram. One thousand grams make a kilogram[1]. 1,000 × 1,000 × 1,000 gives one billion, which is the divisor.
The same divisor applies to every value in between. One hundred micrograms is 0.0000001 kg. One thousand micrograms gives 0.000001 kg, which is one milligram.
In the other direction the number looks like this: one kilogram is 1,000,000,000 micrograms, one billion. The other page of this pair converts in that direction.
The result starts with several zeros after the decimal point, so the converter also gives it as a power of ten. A dose of 400 mcg is 0.0000004 kg, and the line under the result field shows the same value as 4 × 10⁻⁷.
How do you convert micrograms to kilograms? Formula and example
The formula has one factor: kg = mcg ÷ 1,000,000,000. Take the value 45,000 mcg, which is 45 mg. Divide it by one billion and you get 0.000045 kg.
The formula gives three results for round multiples of a microgram. One thousand micrograms is 0.000001 kg, which is one milligram. Ten thousand micrograms gives 0.00001 kg. One million micrograms is 0.001 kg, which is one gram.
Powers of ten make numbers like these easier to work with. The value 0.000045 kg is written as 4.5 × 10⁻⁵, and 0.000000001 kg as 1 × 10⁻⁹. The input field accepts both forms, so you can paste a number copied from a spreadsheet as it is.
The kg to mcg converter converts in the opposite direction, and the mcg to mg converter converts micrograms to milligrams.
How many kilograms is a given number of micrograms?
| Mass in micrograms | Mass in kilograms | Scientific notation |
|---|---|---|
| 1 mcg | 0.000000001 kg | 1 × 10⁻⁹ |
| 5 mcg | 0.000000005 kg | 5 × 10⁻⁹ |
| 10 mcg | 0.00000001 kg | 1 × 10⁻⁸ |
| 15 mcg | 0.000000015 kg | 1.5 × 10⁻⁸ |
| 20 mcg | 0.00000002 kg | 2 × 10⁻⁸ |
| 25 mcg | 0.000000025 kg | 2.5 × 10⁻⁸ |
| 50 mcg | 0.00000005 kg | 5 × 10⁻⁸ |
| 55 mcg | 0.000000055 kg | 5.5 × 10⁻⁸ |
| 75 mcg | 0.000000075 kg | 7.5 × 10⁻⁸ |
| 100 mcg | 0.0000001 kg | 1 × 10⁻⁷ |
| 125 mcg | 0.000000125 kg | 1.25 × 10⁻⁷ |
| 150 mcg | 0.00000015 kg | 1.5 × 10⁻⁷ |
| 200 mcg | 0.0000002 kg | 2 × 10⁻⁷ |
| 250 mcg | 0.00000025 kg | 2.5 × 10⁻⁷ |
| 400 mcg | 0.0000004 kg | 4 × 10⁻⁷ |
| 500 mcg | 0.0000005 kg | 5 × 10⁻⁷ |
| 800 mcg | 0.0000008 kg | 8 × 10⁻⁷ |
| 1,000 mcg | 0.000001 kg | 1 × 10⁻⁶ |
| 1,500 mcg | 0.0000015 kg | 1.5 × 10⁻⁶ |
| 2,000 mcg | 0.000002 kg | 2 × 10⁻⁶ |
| 2,500 mcg | 0.0000025 kg | 2.5 × 10⁻⁶ |
| 5,000 mcg | 0.000005 kg | 5 × 10⁻⁶ |
| 10,000 mcg | 0.00001 kg | 1 × 10⁻⁵ |
| 45,000 mcg | 0.000045 kg | 4.5 × 10⁻⁵ |
How is a microgram written, and where does each spelling apply?
| Spelling | Where it comes from | Where you see it |
|---|---|---|
| µg | SI symbol: the Greek letter mu and the gram symbol | Technical documentation, lab reports, small labels on Irish medicine packs |
| mcg | Spelling with Latin letters only | Supplement and medicine labels in the United States, small labels on English-language packs in the EU |
| ug | Stand-in for µ where a keyboard does not provide the letter | Text fields and files that do not accept the letter µ |
| micrograms | Full name of the unit | Outer carton and package leaflet of medicines in the EU, prescriptions in the United Kingdom |
Which number formats does this converter handle?
| What you type | What the converter shows | How we read it |
|---|---|---|
| 500.5 | 0.0000005005 kg | The decimal point from the numeric keypad, written the way English writes it |
| 500,5 | 0.0000005005 kg | 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 | 0.0000015 kg | 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. |
| 1 000 | 0.000001 kg | A space between thousands, the way a spreadsheet pastes it, does not split the number in two |
| 3/4 | 0.00000000075 kg | We work the fraction out ourselves, so there is no need to turn it into a decimal first |
| 250½ | 0.0000002505 kg | The ½ character copied from a recipe or a label is added to the number in front of it |
| 500.5 µg | 0.0000005005 kg | A unit symbol pasted along with the number is no trouble: we take the number and leave the symbol out |
| 2.6e-3 | 0.0000000000026 kg | Scientific notation, the way a spreadsheet shows very small numbers, is read as it stands |
How do you read a value in micrograms and write it in kilograms?
The steps follow one specific case: the value 250 mcg copied from a label into a spreadsheet.
Check which spelling of the unit you see
A label may show µg, mcg or the full word micrograms. All three mean the same unit, so you copy the value exactly as you see it.Enter the number alone in the converter field
Type 250 into the field, without the unit. The result 0.00000025 kg appears as you type.Use the power of ten if the spreadsheet cuts off zeros
The Scientific notation line under the result shows 2.5 × 10⁻⁷. Spreadsheets accept this value as 2.5e-7 and keep all of its significant digits.Copy the result with the Copy result button
The number goes to the clipboard exactly as it appears in the field. The Swap order button opens the reverse conversion and takes the result with it, so the field on that page already contains 0.00000025 kg.
Billion or milliard? How other languages name 1,000,000,000
In English, the number that separates a microgram from a kilogram is one billion, 10⁹. This is the short scale. The UK government adopted it in 1974 and uses it for all official purposes[6].
Most countries in continental Europe use the long scale, and so do most French-, German- and Spanish-speaking countries. In the long scale a billion is one million million, 10¹², and 10⁹ can have a name of its own: milliard[6]. When you copy a value from a document in one of these languages, go by the digits, and write the name in your own language.
NIST gives this difference as a reason to avoid the names of numbers from 10⁹ upwards and to avoid ppm, ppb and ppt. It prefers powers of 10 for expressing large numbers[7]. The notation 10⁹ reads the same in every language, which is why the converter shows the power of ten under the result field for every value from one thousand upwards and below one hundredth.
Convert other units to Kilograms
Convert Micrograms to other units
Sources
- NIST Guide to the SI, Chapter 4: Table 1 (SI base units) and Table 5 (SI prefixes) — National Institute of Standards and Technology
- NIST Guide to the SI, Chapter 6, Section 6.2.7: Prefixes and the kilogram — National Institute of Standards and Technology
- Compilation of QRD decisions on stylistic matters in product information (EMA/25090/2002), entry “Units: micrograms” — European Medicines Agency
- Microgram — Wikipedia
- 21 CFR 101.36: Nutrition labeling of dietary supplements, paragraph (b)(2)(ii)(B) — U.S. Government Publishing Office (eCFR)
- Long and short scales — Wikipedia
- NIST Guide to the SI, Chapter 7, Section 7.10.3: ppm, ppb and ppt — National Institute of Standards and Technology
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 micrograms to kilograms
How do you convert micrograms to kilograms in a spreadsheet?
Enter a division by one billion in a cell, for example =A2/1000000000. The spreadsheet shows the result in exponential form: for 250 mcg that is 2.5E-07. The converter field accepts the same notation, so you can paste values in both directions without retyping zeros.
Which is bigger, mg or mcg?
The milligram is bigger. One milligram is one thousand micrograms, so 500 mg is 500,000 mcg. A dose written as 500 mcg is one thousand times smaller than 500 mg. Any other value in milligrams can be converted with the mg to mcg converter.
How many kilograms is 1000 mcg?
One thousand micrograms is 0.000001 kg, or 1 × 10⁻⁶. The same mass is one milligram.
Can a medicine label in the EU say “mcg”?
The European Medicines Agency asks for the unit name to be spelled out in full on the outer carton and in the package leaflet. On a small immediate label with limited space, English-language packs may use “mcg”, while France accepts no abbreviation at all[3].
Does the field accept scientific notation?
Yes. The field accepts 4.5e4 and 4.5 × 10⁴, as well as a decimal point or comma. A result below one hundredth gets a Scientific notation line under the field. If the entry cannot be read as a number, the message “This number cannot be converted” appears under the field with an example of a valid entry.
Why does the result in kilograms have so many zeros after the decimal point?
Because the microgram and the kilogram are nine orders of magnitude apart. Even 45,000 mcg is only 0.000045 kg. For values like these a power of ten is easier to read.
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