Capacity

Capacity refers to the amount that can be held in a container. Capacity can be measured in metric units or in U.S. customary units.

Metric Units

The standard metric unit of capacity is the liter.

From the liter, we get the rest of the metric units using the standard metric prefixes.

The eye dropper in the figure has a $2$ ml of liquid.

U.S. Customary Units

The system for measuring capacity in the customary system is based on cup, fluid ounces, pint, quart and gallon.

In the figure shown, $2$ cups of water is equal to $1$ pint.

The most commonly used customary units of capacity are shown.

To convert from one unit to another, we can use unit analysis . For Example, a glass of milk is greater than an eyedropper and less than a small pitcher. Then estimate the capacity of glass of milk.

We know that, $1$ liter = $\mathrm{1,000}$ milliliters.

A small pitcher can fill about $4$ glasses.

One estimate for the capacity of a glass of milk is about $1,000÷4$ or $250$ milliliters.

Note:

$\left(\text{a}\right)$ To convert from larger units to smaller units, multiply by the appropriate unit ratio.

$\left(\text{b}\right)$ To convert from smaller units to larger units, multiply by the reciprocal of the appropriate unit ratio.

$\left(\text{c}\right)$ Multiplying or dividing by a unit ratio is mathematically equivalent to using a proportion to convert between units of measure .