Have you ever wondered how much water you would need for a hike that lasted a few days?

After learning about snakes, Kevin began planning an imaginary hiking trip to the rainforest. He figured that sweating was definitely going to happen given the temperatures and activity. Here is what he discovered in a book.

**
The average person needs 1 gallon of water to drink per day.
**

Kevin can't believe this. He knows that 1 gallon is equal to 128 fluid ounces.

If Kevin went hiking for three days, how many fluid ounces of water is that? How many quarts of water?

**
This Concept is all about identifying equivalent customary units of capacity. Pay attention and you will know how to answer these questions at the end of the Concept.
**

### Guidance

We just finished learning about
**
equivalence
**
regarding customary units of weight. We can also find equivalent measures for customary units of

**. By capacity, we mean volume or the amount of liquid an item can hold. Sometimes, we hear the word capacity with containers or with a milk jug that is one gallon. There are several customary units of capacity.**

*capacity*
**
What are the customary units of capacity?
**
Here are the common units from the smallest to the largest.

- Fluid ounces (fl. oz)
- Cups
- Pints
- Quarts
- Gallons

**
Sometimes, you will have to figure out how many cups are in a pint or how many quarts are in a gallon. Often, these types of conversions are necessary when you are doing an activity involving liquids, like cooking. To convert different units of capacity, you need to know how much of one unit is equal to another unit.
**
**
Here is a chart to show you equivalent customary units of capacity.
**

**
To use the table, make sure you match up one of the red numbers with the units you are changing to. For example, the basic relationship between cups and fluid ounces is 1 cup = 8 fl oz. Between quarts and pints, the basic relationship is 1 qt = 2 pt. Between gallons and pints: 1 gal = 8 pt.
**

How many cups are in 36 fluid ounces?

First, figure out if you need to multiply or divide? Check units.

fluid ounces (small) to cups (large) =
**
DIVIDE
**

**
Next, Divide by what? Go to the table.
**

**
8 fl oz = 1 cup = DIVIDE BY 8
**

Finally, Calculate. 36 8 = 4 cups

**
Our answer is
**
**
cups or 4.5 cups.
**

How many ounces are there in 4 quarts?

First, figure out if you need to multiply or divide. Check units.

quarts (large) to ounces (small) =
**
multiply
**

**
Next, multiply by what? Go to the table.
**
**
32 fl. oz = 1 qt = Multiply by 32.
**

Finally, Calculate. 32 4 128 fluid ounces

Next, it is time for you to practice. Use the chart to find equivalent units.

#### Example A

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5 quarts
**
= ____
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pts.
**

**
Solution: 10 pints
**

#### Example B

**
6.5 gallons
**
= ____
**
quarts
**

**
Solution: 26 quarts
**

#### Example C

**
16 fl. ounces
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= ____
**
cups
**

**
Solution: 2 cups
**

Now back to Kevin and the water. Here is the original problem once again.

After learning about snakes, Kevin began planning an imaginary hiking trip to the rainforest. He figured that sweating was definitely going to happen given the temperatures and activity. Here is what he discovered in a book.

**
The average person needs 1 gallon of water to drink per day.
**

Kevin can't believe this. He knows that 1 gallon is equal to 128 fluid ounces.

If Kevin went hiking for three days, how many fluid ounces of water is that? How many quarts of water?

To figure the fluid ounces, we can multiply the number of fluid ounces in one gallon by three days of hiking.

fluid ounces

To figure out the number of quarts, we can multiply the number of quarts in one gallon by three.

4 quarts = 1 gallon

There are 12 quarts needed for three days of hiking.

### Vocabulary

- Fluid Ounce
- the smallest common unit for measuring liquid capacity. A baby bottle is measured in fluid ounces.

- Cup
- a common small unit for measuring liquid capacity.

- Pint
- 2 cups is equal to one pint of liquid capacity.

- Quart
- 2 pints is equal to one quart of liquid capacity.

- Gallon
- the largest common unit of liquid capacity

### Guided Practice

Here is one for you to try on your own.

Marcus has a 5 gallon jug of water. How many ounces is that?

**
Answer
**

To figure this out, we first have to look at the equivalent units between ounces and gallons.

There are 128 fluid ounces in 1 gallon.

Marcus has a 5 gallon jug.

We need to multiply 128 times 5.

**
The answer is 640 fluid ounces.
**

### Video Review

James Sousa Converting Between Units of Weight in the Customary System

### Practice

Directions: Convert each customary unit of capacity to an equivalent form.

1. 3 cups = ____ fl. oz.

2. 32 fl. oz = ____ cups

3. 4 cups = ____ pints

4. 8 pints = ____ cups

5. 2 quarts = ____ pints

6. 8 gallons = ____ quarts

7. 24 quarts = ____ gallons

8. 2 quarts = ____ gallons

9. 1 gallon = ____ pints

10. 16 fl. oz = ____ pints

11. 2 gallons = ____ fl. oz.

12. 10 gallons = ____ fl. oz.

13. 384 fl. oz = ____ gallons

14. 384 fl. oz = ____ pints

15. 384 fl. oz = ____ cups