Skill: Choose appropriate units of capacity

Capacity tells how much liquid a container can hold.

• Use milliliters (mL) for small amounts, such as a spoonful, medicine cup, or juice box.
• Use liters (L) for larger amounts, such as a pitcher, bucket, or bathtub.
• Remember: $1$ liter equals $1{,}000$ milliliters.

Example: A pitcher holds about $2$ ___ of water. Should the unit be milliliters or liters?

1. Think about the size of the container. A pitcher is large and holds much more than a small cup.
2. Compare the units. A milliliter is a very small amount. A liter is a larger amount.
3. Choose the unit that makes sense: liters.

So, the pitcher holds about $2$ liters of water. If written in milliliters, this is $2 \times 1{,}000 = 2{,}000$ milliliters, which also shows that liters are a better unit for this large container.