Measurement

Measurements are ways that we tell others how much of an item we have. There are two systems of measuring things—English and Metric. English measurements are used only in the United States, while metric measurements are used in nearly every other country. Measurements are used to give number values to distance (length, width, and height), weight, time, volume (liquid measurements), and temperature.

To get you used to these measurements, we’re providing a list of commonly used English and metric measurements, and their equivalents.

Common English Measures

Common Metric Measures

The metric system is also divided into different categories of measurement, but it has a base unit for each category. A base unit means that that is what the category is usually (but not always) measured in, and all the other terms of measurement in that category are built from the base unit.

Universal Measures

Metric Prefixes

There are metric prefixes that you should memorize in order to help you determine metric measurements. They are, from smallest to largest:

Each of these prefixes would go in front of a base unit. Take, for example, length. The base unit for length is the meter. However, we could put a larger prefix, like kilo, in front of it: kilometer (km). Now, it means 1000 meters, because kilo means 1000. We could also put a smaller prefix on it, such as centimeter (cm). Now, it means 1/100 of a meter, or .01 meter.

You also might notice that all of the metric prefixes are multiples of 10 (1, 10, 100, 1000, etc). This makes converting from one to the other far easier than English measures, because you are always multiplying or dividing by 10; remember, multiplying and dividing by 10 simply involves moving the decimal.

English to English Conversions

Most often, if you live in the US, you will be performing English to English conversions between measurements. Converting involves multiplying or dividing by a conversion factor, most of which are listed above. When you are going from smaller units to larger units, you would divide, and when you are going from larger to smaller units, you multiply.

For example, if you wanted to convert days to hours, you would first stop and think: which is larger, a day or an hour? A day is larger, so you would think, how would one convert from larger to smaller units? Well, as we said, larger to smaller units is when you multiply, so you would multiply by the conversion factor, which is 24 since there are 24 hours in 1 day.

The actual problem would look like this: Convert 3 days to hours.

3 days x 24 hours = 72 hours

We would use 24 hours because are 24 hours per every one day, and right now we have 3 days that we want to convert to hours. Converting back would look like the opposite. For example: Convert 72 hours to days.

72 hours / 24 hours = 3 days

Here, we used 24 hours again, because we know there are 24 hours in every 1 day, and we want to see how many days we’ll have if we have 72 hours.

Let’s practice this some more. Convert 3 yards into feet.

First, think “which is larger, yards or feet?”

Realize that yards are larger than feet, so you are converting from larger to smaller. This indicates multiplication.

Find the conversion factor—3 feet in 1 yard. Therefore, you’ll be multiplying by 3.

You can set it up like this: 3 yards x 3 feet = 9 feet

We use 3 feet because there are 3 feet in every yard, and we want to find out how many feet are in 3 yards. Thus, our final answer is 9 feet.

When using conversions, you have to make sure that you are converting to another unit within the same area. For example, so far we have converted units of time (days to hours, and vice versa) and then we converted units of distance (yards to feet), and this is normal. There is no way, however, to convert from days to yards, or from pounds to degrees Fahrenheit, and so on. If you start with distance, you must end with distance; if you start with time, you must end with time, and so on.

Metric to Metric Conversions

Metric to metric conversions are less common—but easier to perform—than English to English conversions. The metric system is based on powers of ten, meaning 10, 100, 1000, 10000, 100000 and so on.

The same rules for conversions still apply when you’re doing metric to metric conversions as do English to English conversions. For example, larger to smaller units still multiply and smaller to larger units still divide. The only change is in the conversion units; instead of being random, now they are all powers of ten.

Let’s try an example of this. Convert 3 meters to centimeters.

First, think: which is larger, a meter or a centimeter? You would conclude that a meter is larger than a centimeter. Therefore, we are going to multiply by the conversion factor. You would look in the table above for the conversion factor from m to cm, and see that there are 100 cm in a m, so you’d be multiplying by 100.

The actual problem looks like this:

3 m x 100 cm = 300 cm

We would use 100 cm as our conversion factor, because there are 100 cm in 1 m. Thus, our final answer is 300 cm.

We’ll do one more before we give you a few to try on your own. This time, convert 2000 grams into kilograms.

First, think: which is larger, a kilogram or a gram? You would conclude that a gram is smaller than a kilogram. Therefore, we are going to divide by the conversion factor. You would look in the table above for the conversion factor from g to kg, and see that there are 1000 g in a kg, so you’d be dividing by 1000. Here’s the work:

2000g / 1000g = 2 kg

We use 1000 g because there are 1000 grams in a kilogram. Thus, our final answer is 2 kg.

English to Metric Conversions

Here is a conversion chart of many of the common English to metric conversions. English measures are on the left and metric measures are on the right.

Temperature

To convert from degrees C to degrees F

(deg C x 9/5) + 32

To convert from degrees F to degrees C

(deg F – 32) x 5/9

Now let’s practice converting between the two. Using this chart, if you’re going from English to metric, you would multiply. If you’re going from metric to English, you’d divide.

Here are a few examples:

Convert 4 lbs to kg.

First, you know that you’re going from English to metric, so you know you’ll be multiplying. We know that there are .5 kg in each lb, so we set up our equation like this:

4 lb x .5kg = 2 kg

Thus, 2 kg is our final answer.

Now, let’s practice going from metric to English.

Convert 200 milliliters to cups.

First, you know that you’re going from metric to English, so you know you’ll be dividing. We know that there are 237 mL in each cup, so we set up our equation like this:

200 mL / 237 mL = .84 cups

We use 237 mL because there are 237 mL in a cup. Thus, .84 cups is our final answer.

Notice that we divide when we are moving from metric to English, we divide; when we move from English to metric, we multiply.