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Lesson 2: Estimating volume

# U.S. customary units: fluid volume

Sal discusses US customary units of volume or capacity such as teaspoon, fluid ounce, cup, pint, quart, and gallon. Created by Sal Khan.

## Want to join the conversation?

• How many liters are in a gallon, or how many gallons are in a liter?
• Just keep in mind, the gallon is a US customary unit, while a liter is a metric unit.

1 gallon = 3.78 liters
1 liter = 0.26 gallon
• What units are used in science in U S ? I have an impression that this units are not pricise enough correct and fixed measurements.
• SI units (i.e. metric units) are generally used for science in the US, certainly for measuring the mass of objects.
• How many teaspoons are in a gallon?
• Here's the answer, & my work: 3 teaspoons = 1 tablespoon. 3 teaspoons times 2 tablespoons = 6 teaspoons or 1 fl. ounce. 6 teaspoons times 8 fl. ounces = 48 teaspoons or 1 cup. 48 teaspoons times 2 cups = 96 teaspoons or 1 pint. 96 teaspoons times 2 pints = 192 teaspoons or 1 quart. 192 teaspoons times 4 quarts = 768 teaspoons or 1 gallon. There are 768 teaspoons in 1 gallon.
• Is there a bigger measurement than gallons?
• Hi, Apikaila Kanake :)

They represents larger quantities than the gallon.

I noticed that it's better to use gallons or the metric system, because barrels and hogsheads are confusing; they express a variety of quantities depending of the context or other specifications. You can see what I'm talking about at the links bellow.
http://en.wikipedia.org/wiki/Barrel_%28unit%29
• Where did teaspoon, tablespoon, fluid ounce, cup, pint, quart and gallon come from?
• Most of these measurements came from ancient apothecaries who needed measurements for their medicinal recipes. Back then, they compounded the recipes in the pharmacy itself, so everyone needed the same recipe. They used pints, fluid ounces, drachms (drams), scruples, and minims. A teaspoon is about the measurement of a dram, and was an unofficial measuring unit used by these apothecaries to represent one dram. All of their measurements came from earlier Roman systems of measurement, and most of these came about because of merchants and trade.

When people want to trade things, they need to know about how much stuff they are getting. Gallons are related to the old-fashioned term bushel. People needed to know about how much a bushel was, and if they paid a certain amount of gold for a certain number of bushels, how much exactly were they getting. Quarts and gallons are primarily units of trade, and for a long time there wasn't a standard version, although a quart was always a quarter of a gallon (hence the name). For one thing, there was an "ale gallon" and a "wine gallon" because these items came in two different sized containers!

Almost all measurements from the U.S. customary system date back to the Roman Empire, pre-colonial merchants and traders, and these early pharmacists.

The metric system, which was an attempt to bring order to all of these various different measurements, happened much later in France after the French Revolution.
• Is there any way to remember this chart better? I mean, Sal did a great job but I still find it confusing.
• we don't use gallons, ounces, pounds, pints and quarts in Australia! How am I meant to learn this?
• Learn how to convert gallons, ounces, pounds, pints, and quarts to your Australian metric systems.
• How do you know if a spoon is a teaspoon or table spoon?