Description: Learn about metric units of volume or capacity such as milliliter and liter. Created by Sal Khan. Let's think a little bit about the metric system units for volume, or essentially how much space something is taking up in three dimensions. One way you could think about a liter is if you took a cube that is 10 centimeters deep, 10 centimeters wide, and 10 centimeters tall, then this amount of space that you're taking up, this volume is 1 liter. At least in the US, oftentimes soda, and other things, will be sold in these 2-liter bottles.*Teacher Advisor is 100% free.