Convert milligrams to kilograms
Type a value in milligrams and read the result in kilograms. One kilogram is a million milligrams, so a 500 mg dose comes to 0.0005 kg. The result appears as you type, and the page also has a table of label values along with the same result in scientific notation.
How many kilograms is a given number of milligrams?
Divide the number of milligrams by a million and you have the value in kilograms. A 500 mg dose works out at 0.0005 kg.
Formula: kilograms = milligrams ÷ 1,000,000
The million comes from two steps of a thousand. A thousand milligrams make one gram and a thousand grams make one kilogram, so the product of both steps is a million.
The same sum works in your head: move the decimal point six places to the left. 2,000 mg becomes 0.002 kg. 250 mg becomes 0.00025 kg.
The conversion is exact to the last digit, because milli stands for one thousandth and kilo for a thousand, and both are powers of ten[1].
Milligrams are printed on a medicine box or a supplement label, while kilograms are read off a scale or a materials spec. Label doses therefore give numbers that begin with a decimal point and several zeros.
For the opposite direction use the kilograms to milligrams converter.
What is a milligram and what is a kilogram?
A milligram is one thousandth of a gram. In the SI the prefix milli means exactly one thousandth, or 10⁻³[1], so the symbol is built from that prefix and the letter g.
The kilogram is the SI base unit of mass and the only base unit whose own name carries a prefix[2]. Since 2019 its value has been based on a constant of nature: the definition fixes the numerical value of the Planck constant at 6.626 070 15 × 10⁻³⁴ when expressed in the unit joule second[3]. Before that the standard was a cylinder of platinum–iridium alloy, the International Prototype of the Kilogram.
That single name sets the spelling rule for every unit of mass: prefixes attach to the gram. A milligram is a millionth of a kilogram, and its symbol is still formed from the gram — NIST gives the correct form outright as 1 mg[1].
The gram is between those two units, and the microgram is a thousand times smaller than the milligram.
How many kilograms are 100 mg, 500 mg and 1000 mg?
| Milligrams | Kilograms | Scientific notation | Grams |
|---|---|---|---|
| 1 mg | 0.000001 kg | 1 × 10⁻⁶ kg | 0.001 g |
| 2 mg | 0.000002 kg | 2 × 10⁻⁶ kg | 0.002 g |
| 2.5 mg | 0.0000025 kg | 2.5 × 10⁻⁶ kg | 0.0025 g |
| 5 mg | 0.000005 kg | 5 × 10⁻⁶ kg | 0.005 g |
| 10 mg | 0.00001 kg | 1 × 10⁻⁵ kg | 0.01 g |
| 20 mg | 0.00002 kg | 2 × 10⁻⁵ kg | 0.02 g |
| 25 mg | 0.000025 kg | 2.5 × 10⁻⁵ kg | 0.025 g |
| 30 mg | 0.00003 kg | 3 × 10⁻⁵ kg | 0.03 g |
| 40 mg | 0.00004 kg | 4 × 10⁻⁵ kg | 0.04 g |
| 50 mg | 0.00005 kg | 5 × 10⁻⁵ kg | 0.05 g |
| 60 mg | 0.00006 kg | 6 × 10⁻⁵ kg | 0.06 g |
| 75 mg | 0.000075 kg | 7.5 × 10⁻⁵ kg | 0.075 g |
| 80 mg | 0.00008 kg | 8 × 10⁻⁵ kg | 0.08 g |
| 100 mg | 0.0001 kg | 1 × 10⁻⁴ kg | 0.1 g |
| 125 mg | 0.000125 kg | 1.25 × 10⁻⁴ kg | 0.125 g |
| 150 mg | 0.00015 kg | 1.5 × 10⁻⁴ kg | 0.15 g |
| 200 mg | 0.0002 kg | 2 × 10⁻⁴ kg | 0.2 g |
| 250 mg | 0.00025 kg | 2.5 × 10⁻⁴ kg | 0.25 g |
| 280 mg | 0.00028 kg | 2.8 × 10⁻⁴ kg | 0.28 g |
| 300 mg | 0.0003 kg | 3 × 10⁻⁴ kg | 0.3 g |
| 325 mg | 0.000325 kg | 3.25 × 10⁻⁴ kg | 0.325 g |
| 350 mg | 0.00035 kg | 3.5 × 10⁻⁴ kg | 0.35 g |
| 370 mg | 0.00037 kg | 3.7 × 10⁻⁴ kg | 0.37 g |
| 400 mg | 0.0004 kg | 4 × 10⁻⁴ kg | 0.4 g |
| 450 mg | 0.00045 kg | 4.5 × 10⁻⁴ kg | 0.45 g |
| 500 mg | 0.0005 kg | 5 × 10⁻⁴ kg | 0.5 g |
| 550 mg | 0.00055 kg | 5.5 × 10⁻⁴ kg | 0.55 g |
| 600 mg | 0.0006 kg | 6 × 10⁻⁴ kg | 0.6 g |
| 650 mg | 0.00065 kg | 6.5 × 10⁻⁴ kg | 0.65 g |
| 750 mg | 0.00075 kg | 7.5 × 10⁻⁴ kg | 0.75 g |
| 800 mg | 0.0008 kg | 8 × 10⁻⁴ kg | 0.8 g |
| 835 mg | 0.000835 kg | 8.35 × 10⁻⁴ kg | 0.835 g |
| 900 mg | 0.0009 kg | 9 × 10⁻⁴ kg | 0.9 g |
| 1,000 mg | 0.001 kg | 1 × 10⁻³ kg | 1 g |
| 1,200 mg | 0.0012 kg | 1.2 × 10⁻³ kg | 1.2 g |
| 1,500 mg | 0.0015 kg | 1.5 × 10⁻³ kg | 1.5 g |
| 2,000 mg | 0.002 kg | 2 × 10⁻³ kg | 2 g |
| 2,500 mg | 0.0025 kg | 2.5 × 10⁻³ kg | 2.5 g |
| 3,000 mg | 0.003 kg | 3 × 10⁻³ kg | 3 g |
| 3,500 mg | 0.0035 kg | 3.5 × 10⁻³ kg | 3.5 g |
| 4,000 mg | 0.004 kg | 4 × 10⁻³ kg | 4 g |
| 5,000 mg | 0.005 kg | 5 × 10⁻³ kg | 5 g |
| 5,681 mg | 0.005681 kg | 5.681 × 10⁻³ kg | 5.681 g |
| 7,500 mg | 0.0075 kg | 7.5 × 10⁻³ kg | 7.5 g |
| 10,000 mg | 0.01 kg | 1 × 10⁻² kg | 10 g |
| 25,000 mg | 0.025 kg | 2.5 × 10⁻² kg | 25 g |
| 30,000 mg | 0.03 kg | 3 × 10⁻² kg | 30 g |
| 35,000 mg | 0.035 kg | 3.5 × 10⁻² kg | 35 g |
| 50,000 mg | 0.05 kg | 5 × 10⁻² kg | 50 g |
| 92,500 mg | 0.0925 kg | 9.25 × 10⁻² kg | 92.5 g |
| 100,000 mg | 0.1 kg | 1 × 10⁻¹ kg | 100 g |
| 250,000 mg | 0.25 kg | 2.5 × 10⁻¹ kg | 250 g |
| 500,000 mg | 0.5 kg | 5 × 10⁻¹ kg | 500 g |
| 750,000 mg | 0.75 kg | 7.5 × 10⁻¹ kg | 750 g |
| 1,000,000 mg | 1 kg | 1 × 10⁰ kg | 1,000 g |
What is 1 mg/kg in ppm, ppb and percent?
| Content | ppm | ppb | Percent by mass | Micrograms per gram |
|---|---|---|---|---|
| 0.01 mg/kg | 0.01 ppm | 10 ppb | 0.000001% | 0.01 µg/g |
| 0.05 mg/kg | 0.05 ppm | 50 ppb | 0.000005% | 0.05 µg/g |
| 0.1 mg/kg | 0.1 ppm | 100 ppb | 0.00001% | 0.1 µg/g |
| 0.5 mg/kg | 0.5 ppm | 500 ppb | 0.00005% | 0.5 µg/g |
| 1 mg/kg | 1 ppm | 1,000 ppb | 0.0001% | 1 µg/g |
| 2 mg/kg | 2 ppm | 2,000 ppb | 0.0002% | 2 µg/g |
| 5 mg/kg | 5 ppm | 5,000 ppb | 0.0005% | 5 µg/g |
| 10 mg/kg | 10 ppm | 10,000 ppb | 0.001% | 10 µg/g |
| 50 mg/kg | 50 ppm | 50,000 ppb | 0.005% | 50 µg/g |
| 100 mg/kg | 100 ppm | 100,000 ppb | 0.01% | 100 µg/g |
| 500 mg/kg | 500 ppm | 500,000 ppb | 0.05% | 500 µg/g |
| 1,000 mg/kg | 1,000 ppm | 1,000,000 ppb | 0.1% | 1,000 µg/g |
| 10,000 mg/kg | 10,000 ppm | 10,000,000 ppb | 1% | 10,000 µg/g |
| 100,000 mg/kg | 100,000 ppm | 100,000,000 ppb | 10% | 100,000 µg/g |
| 1,000,000 mg/kg | 1,000,000 ppm | 1,000,000,000 ppb | 100% | 1,000,000 µg/g |
How do the mass units compare, from the tonne to the microgram?
| Unit | Symbol | In grams | In kilograms |
|---|---|---|---|
| Tonne | t | 1,000,000 g | 1,000 kg |
| Kilogram | kg | 1,000 g | 1 kg |
| Gram | g | 1 g | 0.001 kg |
| Milligram | mg | 0.001 g | 0.000001 kg |
| Microgram | µg | 0.000001 g | 0.000000001 kg |
Which number formats does this converter handle?
| What you type | What the converter shows | How we read it |
|---|---|---|
| 750.5 | 0.0007505 kg | The decimal point from the numeric keypad, written the way English writes it |
| 750,5 | 0.0007505 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 | 0.0015 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. |
| 1 500 | 0.0015 kg | A space between thousands, the way a spreadsheet pastes it, does not split the number in two |
| 3/4 | 0.00000075 kg | We work the fraction out ourselves, so there is no need to turn it into a decimal first |
| 250½ | 0.0002505 kg | The ½ character copied from a recipe or a label is added to the number in front of it |
| 750.5 mg | 0.0007505 kg | A unit symbol pasted along with the number is no trouble: we take the number and leave the symbol out |
How do you convert milligrams to kilograms in a spreadsheet?
Excel handles this in two ways: plain division, or a built-in function with a list of unit names. These steps cover both.
Type the number of milligrams into a cell
Say it is in cell A1. If you have more values, put them one under another in the same column so the formula from the next step can be dragged down the whole list.Divide that cell by a million
In the next cell type=A1/1000000. For 500 mg the sheet shows 0.0005, and for 250,000 mg it shows 0.25.Or use the CONVERT function
Its syntax isCONVERT(number, from_unit, to_unit)[7]. The gram is coded as "g", the prefix milli as "m" and kilo as "k", so the whole conversion reads=CONVERT(A1,"mg","kg").Set as many decimal places as you need
Dividing by a million moves the answer six places, so set the number of decimals yourself.=ROUND(A1/1000000,9)keeps nine digits after the point, enough for one milligram to stay visible as 0.000001 kg.
What does mg/kg mean on a lab report?
The notation gives a content, meaning a ratio of two masses. It says how many milligrams of a substance there are in each kilogram of the sample, so it stays the same however much of the sample was weighed. If 2 kg of sample contain 1 mg of a substance, the result is 0.5 mg/kg.
In toxicology and pharmacy the same notation describes a dose per kilogram of body mass. The figure then says how many milligrams are given for each kilogram of body mass of the patient or animal, and the specific value comes from the label or the prescriber.
Convert other units to Kilograms
Convert Milligrams to other units
Sources
- Metric (SI) Prefixes — National Institute of Standards and Technology
- Kilogram — Wikipedia
- SI base unit: kilogram (kg) — International Bureau of Weights and Measures (BIPM)
- Pesticide Registration Manual: Chapter 11 — Tolerance Petitions — United States Environmental Protection Agency
- NIST Guide to the SI, Chapter 7: Rules and Style Conventions for Expressing Values of Quantities — National Institute of Standards and Technology
- Writing with SI (Metric System) Units — National Institute of Standards and Technology
- 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 kilograms
How many kilograms is 1000 mg?
0.001 kg, one thousandth of a kilogram. The same mass is exactly one gram, because a thousand milligrams make a gram. Any milligram value goes into grams through the mg to g converter.
How many kilograms is 500 mg?
0.0005 kg, half a thousandth of a kilogram. Written in grams the same mass is 0.5 g.
How do you convert mg to kg in your head?
Move the decimal point six places to the left. 1,000 mg becomes 0.001 kg, 20,000 mg becomes 0.02 kg, and 750,000 mg becomes 0.75 kg.
Is 1 mg/kg the same as 1 ppm?
Yes, when ppm refers to mass. Both then describe one millionth of the mass and give the same figure. A milligram is a millionth of a kilogram, so one milligram per kilogram is one part per million. NIST asks for the mass fraction form, which is the mg/kg spelling.
How do you write the result in scientific notation?
One milligram is 1 × 10⁻⁶ kg, because dividing by a million moves the decimal point six places. A hundred milligrams is 1 × 10⁻⁴ kg, and 2.5 mg is 2.5 × 10⁻⁶ kg. The conversion table has a column with that notation.
Why is the symbol mg when a milligram is a millionth of a kilogram?
Because prefixes of mass attach to the gram. The kilogram is the one SI base unit that already carries a prefix in its name, so further prefixes go on the gram, which is where mg and µg come from. NIST gives 1 mg as the correct form.
Does the field accept fractions?
Yes. You can type a decimal with a point or a comma, such as 2.5 or 2,5, and a common fraction such as 1/2 or 2 1/4. The result appears as you type.
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