ml
Meaning of ml: Concentration is what turns a volume into a dose, which is why milliliters and milligrams can never be swapped for each other.
Definition of ml
mL is the abbreviation for milliliter, the metric unit of volume equal to one thousandth of a liter. It is the working unit for liquid measurement in medicine, covering intravenous fluids, oral liquid medicines, injections and laboratory specimens. One milliliter occupies the same space as one cubic centimeter, so the two units are treated as equal.
Why do milliliters and milligrams get confused?
They measure different things. A milliliter is an amount of space and a milligram is an amount of matter, and nothing converts one into the other on its own. What links them is concentration, written as milligrams per milliliter and printed on the bottle. The same liquid medicine is often sold in more than one strength, so a syringe drawn to the same mark can deliver twice the drug from one bottle as from another. This is why an order written only as a volume is incomplete: the number of milliliters means nothing until the strength of the preparation is known.
How does the unit relate to the others?
| Unit | How it compares |
|---|---|
| Liter | One thousand milliliters |
| Deciliter | One hundred milliliters, common in laboratory results |
| Cubic centimeter | The same volume as a milliliter, often written cc |
| Teaspoon | About five milliliters, though a household spoon is not a measuring device |
Where does the unit cause trouble?
Mostly in handwriting and speech. The abbreviation cc looks like a zero or a pair of them when written quickly, which is why milliliter is preferred in records. Written as ml with a small letter, the l can be mistaken for the digit one, so mL with a capital L is the safer form. Household spoons are the other recurring problem, since a kitchen teaspoon holds anywhere from a little under to well over the nominal five milliliters, and a dosing syringe or cup marked in milliliters removes the guesswork. In the other direction, volume is the unit in which fluid balance is tracked: intravenous fluids are ordered in milliliters per hour, and the tally of what went in and what came out is kept in the same unit so the two can be set against each other.
Also known as
Used in a sentence
The intravenous fluid order specified a rate measured in milliliters per hour.
Good to know
Milliliters measure volume, while milligrams measure mass, so converting between the two for a given medication depends on that medication's specific concentration rather than a fixed, universal relationship.
Word origin
Where “ml” comes from
Formed from milli-, from Latin mille, meaning thousand, indicating one thousandth, and liter, from French litre, ultimately derived from Greek litra, a unit of weight.