How to convert units of measurement

Conversion des unités de mesure

The majority of the world uses systems of measurement that come under the metric system. For example, changing feet to meters or centimeters to meters are unit conversions which help us to differentiate between measurements of length, volume, and weight. 

We have unit systems in place in order to help us decipher and calculate between a combination of units. Simple calculations such as converting kilometers to meters or inches to feet are modern forms of conversion that you will use throughout your lifetime. It is, therefore, important to have a comprehensive understanding of unit conversions. With this in mind, we created this guide to unit conversions. 


Why do we convert units of measurements?

Knowing the units of measurement that correspond with a number gives you so much more information than just having a single digit by itself. 

For example, knowing that 1 cup is 0.250 liters means that I know how much water I’ll need to add to my coffee if I’m measuring out cups instead of milliliters. Similarly, knowing that 5 grams is 0.2 ounces lets me figure out what weight I should put on my scale if I’m weighing grams instead of pounds. Just knowing the unit of measurement that corresponds with a number can help solve math problems, and tell you whether someone else is using metric or imperial measurements.


Where can we find conversion factors?

Conversion factors are numbers that convert one unit into another. They are used in chemistry, physics, engineering, and many other fields. Mathematicians don’t just pull conversion factors out of their hat; there are many sources where you can find them. 

For example, the US National Institute of Standards and Technology (NIST) has a very useful set of general tables of units of measurement. There are also several good sources online.

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4 ways to convert units of measurement

There are many different types of measurement. One way to convert one type to another is by multiplying or dividing. At other times, you will need to know custom unit systems that are used in a particular place along with both the representations of units if you want to be able to make the conversion. These unit conversion algorithms can usually easily be found in a unit conversion table. 

1. Converting a larger unit to a smaller unit

If you want to convert a larger unit to a smaller unit, such as liters into milliliters, you first divide the larger amount by the smaller amount. Next, multiply the answer you got by the original larger amount.

2. Converting a smaller unit to a larger unit

To convert a smaller amount into a larger one, divide the larger quotient of unit by the many smaller composite units it would take to fit into it.

3. Converting units of measurement in the same system

Imagine you are a caterer for a party going shopping to get flour. You need 200 grams of flour per cookie batch and need to make 30 batches. You can buy a five kilo bag of flour but aren’t sure if that will be sufficient. In order to work out whether you have enough flour, it is best to convert both measures into the same unit so that you can compare them.

To do this, you need to know how much 1kg of flour weighs, and then divide your amount by that weight. Let’s say that 1kg of flour weighs 707g. Your amount would then be 707/1000 or 0.707kg. Following this, you simply add a zero after the number to indicate that it is a whole number of kilograms. As a result, your final answer would be 0.7kg.

4. Converting units of measurement in different systems

When performing these conversions, you’re converting between metric and imperial measurements. Metric measures are very common worldwide, but there are still places in the US where they use Imperial units, such as inches, feet, gallons etc. 

While countries in the British Commonwealth, including Canada, officially use the metric system, now known as the international system of units, there are certain situations where you might find yourself needing to convert a metric measurement into an Imperial one. The only way you can make these conversions is if you know the exact conversion rates of base units.


Key conversions to know

In some cases, you simply need to know the unit for conversion as no numeric conversion factor will be able to bring you to the simple unit value that you need. While there are some abstract units out there that you might never use, below are some of the most common base unit relations:

  • Pounds to Kilograms: 1 kg = 2.2 lb
  • Gallons to Liters: 1 gal = 3.785 L
  • Feet to Meters: 1 ft = 0.305 m
  • Miles to Kilometers: 1 mi = 1.61 km
  • Cups to Milliliters: 1 c = 240 mL
  • Inches to Centimeters: 1 in = 2.54 cm
  • Ounces to Grams: 1 oz = 28.3 g


Math tutoring services

There are many things that you learn at school which you will need to use in real life, such as unit conversion. It is, therefore, extremely important to understand the intricacies that underlie the relationships between the various units. However, this can be challenging for students.

This is why Tutorax provides one-on-one tutoring services designed to help you better understand mathematical concepts that are hard to grasp at school. We offer both in-person and online tutoring services to fit your needs and schedule. In addition to math, we offer tutoring services in a variety of subjects including:

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