In spite of the efficient and streamlined nature of the metric system, other measurement systems still exist and are used with varying degrees of frequency. Some countries still use the imperial system or a mixture of the imperial and metric systems. Two of the most common volume units in the imperial system are the gallon (gal) and the fluid ounce (fl oz). Gallons are roughly on the same scale as liters and are commonly used to describe things such as the price of gas or the amount of liquid found in grocery store items such as milk and juice. Fluid ounces exist on a smaller scale and can be used to describe the amount of a liquid ingredient needed in a recipe or the volume of liquid found in convenience store drinks, such as sodas. Additionally, units such as cups and teaspoons are used to describe the volume of solid ingredients needed in recipes when using the imperial system.
However, even though the imperial system is still used, the metric system is by far more common, and scientists use the metric system exclusively. This is because each prefix in the metric system changes the base unit by some factor of ten, which is extremely convenient. The use of prefixes in the metric system also eliminates the need to memorize different units when measuring different quantities, since each prefix can be attached to any base unit, regardless of what it is measuring.
| Imperial Unit | Metric Equivalent |
|---|---|
| 1 gallon | 3.79 L |
| 1 fluid ounce | 30 mL |
| 1 cup | 250 mL |
| 1 teaspoon | 5 mL |
To unlock this lesson you must be a Study.com Member.
Create your account
Dimensional analysis is the most common technique used to convert between amounts. For example, a contractor accepts a request to build a pool containing 37,854 L of water. What would that be in kL? He knows that the conversion factor between L and kL is 1kL=1000L, so the calculation goes as:
$$\frac{37584 \text{L}}{1}\times\frac{1\text{kL}}{1000\text{L}}=37.584\text{kL} $$ When performing conversions using cubic volume units, a bit more caution must be exercised. Since the units being used are cubed, the conversion factor being used must also be cubed. If a recipe calls for 0.0039m{eq}^3 {/eq} of vinegar, What is the equivalent amount in mL? Since 1mL=1cm{eq}^3 {/eq}, converting from cubic meters to cubic centimeters will then yield the answer.
$$\frac{0.0039 \text{m}^3}{1}\times\frac{(100\text{cm})^3}{(1\text{m})^3}=3.9\times10^3\text{cm}^3=3.9\times10^3\text{mL} $$ Note how the given value was not cubed during the calculation. This is because the initial value was acquired via measurement, so the dimensions of the value have already been taken into account.
To unlock this lesson you must be a Study.com Member.
Create your account
While metric units are the standard in the majority of the world, imperial units are used frequently enough that it is beneficial to know how to convert between the two. It is worth noting that in most cases, conversion factors, which allow for going back and forth between metric and imperial units, are not exact. For example, it is common to see 1 gallon being the same as 3.8 liters, when in fact the exact conversion carries the value in liters out to nine decimal places. In the following examples, the approximate conversion factors will be used.
Consider an American woman who has just moved to Spain. She knows her car holds 20 gallons of gas, but gas in Spain is sold by the liter. How many liters will it take to fill her car? Using the conversion factor given above, the amount in liters is calculated to be:
$$\frac{20 \text{gal}}{1}\times\frac{3.8\text{L}}{1 \text{gal}}=76.0 \text{L} $$
Next, imagine a man who is about to cook dinner for his family. He has recently purchased a Chinese cookbook and the recipe he is making calls for 20 mL of rice vinegar. However, he only has devices that measure in fluid ounces. How many fluid ounces will he need? Knowing that 1 fl oz = 15 mL, the calculation goes as:
$$\frac{20\text{mL}}{1}\times\frac{1\text{fl oz}}{15\text{mL}}=1.33 \text{fl oz} $$
Finally, consider Jamie who just purchased an aquarium that holds 420 L of water. What is the volume of water, in gallons, that Jamie needs to fill the tank? Again, using the above conversion factor, the required volume is found to be:
$$\frac{420\text{L}}{1}\times\frac{1\text{gal}}{3.8\text{L}}=110.5 \text{gal} $$
To unlock this lesson you must be a Study.com Member.
Create your account
The SI unit for measuring volume is cubic meters (m{eq}^3 {/eq}), but it is also common to see units of liters (L), or cubic centimeters (cm{eq}^3 {/eq}.
The prefix system used in the metric system makes it the standard for scientists and most countries. Since each prefix is some factor of 10, using the metric system can allow for easier calculations and conversion between units. However, some countries and businesses still use the imperial system, which can measure volumes in gallons, fluid ounces, cups, and teaspoons.
To unlock this lesson you must be a Study.com Member.
Create your account
Additional Info
Metric System vs. Standard System
Do you find yourself saying any of the following?
- I need 5 milliliters of baking soda to make these cookies.
- I'd like to buy a liter of milk.
- Can you pass me my 250 mL mug?
No? Okay, that's probably because you live in the United States where we primarily use United States customary units which were developed from English units used during the British Empire. As a result, tablespoons, gallons, and cups probably sound more familiar to you, but the metric system is the system of measurements used throughout most of the world and by scientists everywhere, even in the United States.
This lesson will help you begin to navigate the world of the metric system, primarily the metric units of volume, or the space an object takes up. A unit, by the way, is the type of measurement used and is represented by a symbol. For example, we have already talked about many different units of measurement including cups, liters, and gallons.
Liter and Milliliters
One of the most common metric units of volume you will come across is the liter. Even though the United States doesn't use the metric system, you will find that liters are used all over the place. A liter is represented by the symbol L and is approximately 4 cups. The next time you go to the grocery store, check out the volumes of different drinks and you'll likely see liters are used exclusively or alongside typical US measurements.
 |
While you'll probably run into liters quite often at the grocery store, you are probably equally likely to see milliliters, which are represented by the symbol mL. The prefix 'milli' means 1/1000th, so there are 1,000 mL in 1 L. There are approximately 5 mL in one teaspoon.
 |
Take a look at the table to see some everyday items that are liters or milliliters.
| Item | Volume |
|---|---|
| Popular water bottles | 1000 mL (or 1 L) |
| A coffee or tea mug | 250 mL |
| 1 teaspoon | about 5 mL |
| A large bottle of soda | 2 L |
Other Metric Units
The key to navigating the metric system is to learn the prefixes. You already know that the the prefix milli means 1/1000th, but there are other prefixes too! Take a look at the table to see some prefixes and what they mean.
| Prefix | Meaning | Unit | Symbol |
|---|---|---|---|
| milli | 1/1000th of a L | milliliter | mL |
| centi | 1/100th of a L | centiliter | cL |
| deci | 1/10th of a L | deciliter | dL |
| deca | 10 L | decaliter | daL |
| hetco | 100 L | hectoliter | hL |
| kilo | 1000 L | kiloliter | kL |
Now you probably won't see centiliters, deciliters, decaliters, hectoliters, and kiloliters at a grocery store in the United States, but let's still take a moment to compare them to some measurements you are familiar with. There are about 1.5 cL in 1 tablespoon, about 2.5 dL in about one cup, 1 daL is approximately 2.6 gallons, 1 hL is a little over 26 gallons and 1 kL is about 264 gallons. Don't worry if this seems odd! The metric system is simple to convert to a different unit that might be easier to think about!
Lesson Summary
The metric system is utilized by most of the world. Although the United States uses a non-metric standard, a few metric units have seeped in. You can get on the same page as scientists and the rest of the world by learning a few metric units of volume.
- Liters are represented by an L and is equivalent to approximately 4 cups. If you go to the store, you can easily find some substances measured in liters. For example, next time you are buying soda take a look at the volume. It's probably measured in liters!
- Milliliters are smaller than liters. In fact there are 1,000 milliliters in 1 L. Milliliters are represented by an mL and 1 teaspoon is about 5 mL.
- Learning prefixes will help you navigate the metric system. Although centiliters, deciliters, decaliters, hectoliters and kiloliters aren't as commonplace as liters and milliliters, it's worth taking some time to memorize the prefixes. This will help you when you are learning metric units of length and mass.
To unlock this lesson you must be a Study.com Member.
Create your account
