Milliliter — Definition, Formula & Examples

A milliliter is a very small unit for measuring liquid volume in the metric system. One milliliter (mL) equals one-thousandth of a liter, roughly the amount of water that fills a small eyedropper.

A milliliter (symbol: mL) is a metric unit of capacity defined as exactly $\frac{1}{1{,}000}$ of a liter, equivalent to one cubic centimeter ( $1 \text{ cm}^3$ ).

Key Formula

1 \text{ L} = 1{,}000 \text{ mL}

Where:

$L$ = liters, the standard metric unit of volume
$mL$ = milliliters, each equal to one-thousandth of a liter

How It Works

You use milliliters to measure small amounts of liquid, such as medicine doses or ingredients in a recipe. To convert between milliliters and liters, remember that 1,000 mL make up 1 liter. If you know a volume in liters, multiply by 1,000 to get milliliters. If you have milliliters, divide by 1,000 to get liters.

Worked Example

Problem: A water bottle holds 2 liters. How many milliliters is that?

Set up the conversion: Since 1 liter equals 1,000 milliliters, multiply the number of liters by 1,000.

2 \times 1{,}000 = 2{,}000

Answer: The water bottle holds 2,000 mL.

Why It Matters

Milliliters appear on medicine labels, drink containers, and cooking measurements. Understanding this unit helps you follow recipes accurately and take the correct dose of liquid medicine.

Common Mistakes

Mistake: Confusing milliliters (mL) with milligrams (mg).

Correction: Milliliters measure volume (how much space a liquid fills), while milligrams measure mass (how heavy something is). Check the unit abbreviation carefully.