The metric system

Jump into the measurement system that is used around the world.

Author
Taylor Hartley

Expert Reviewer

Published: February 2024

The metric system

Jump into the measurement system that is used around the world.

Author
Taylor Hartley

Expert Reviewer

Published: February 2024

The metric system

Jump into the measurement system that is used around the world.

Author
Taylor Hartley

Expert Reviewer

Published: February 2024

Key takeaways

• Metric is a worldwide standard – While some countries maintain their own, distinct units of measure, the metric system has been embraced around the world.
• Measure all sorts of things – The metric system covers length, weight, and volume with easy-to-remember increments.
• Zeros are the heroes – Usually, metric units are determined by how many zeros there are in the number. Each new zero is a new metric conversion.

The metric system is all around you. Grab the nearest bottle of soda or bag of chips and you’ll likely see litres or grams listed somewhere on the label. But what do these words mean? Let’s dive in and find out!

What is the metric system?

The metric system is a way to measure the world, just like the customary/imperial system used in America. Instead of thinking in miles when planning a trip, people who use the metric system think in kilometres. And this is a far more common way of measuring the world. Countries all over, from France to Japan to Ethiopia, use the metric system in industry and everyday life.

What makes the metric system so popular? Well, for one, having a uniform measurement system makes collaboration across borders much simpler. Additionally, it is also very easy to understand and calculate.

The metric system is built around three main base units:

• Metre – Use variations of this to measure length and distance. One metre is about the length of a professional baseball bat.
• Gram – This unit is for weight. A paperclip or an American dollar bill weighs around a gram.
• Litre – This unit measures volume. Litres are easy, since you probably know this unit already. Most sodas come in two-litre bottles in the grocery store, and a quart of milk is very close to one litre.

From these base units, you can get the rest of the units in the metric system by adding prefixes to metre, gram, or litre. For example, something that is 1000 metres long is 1 kilometre because kilo means thousand. This is also true for grams and litres, which makes remembering the different units very simple.

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Metric units

Check out the list below of the metric conversions we see used most often in everyday life:

• Length — Used to measure how wide or tall something is.
• Millimetre (mm)
• Decimetre (dm)
• Centimetre (cm)
• Metre (m)
• Kilometre (km)
• Weight — Used to measure how heavy something is.
• Gram (g)
• Kilogram (kg)
• Capacity — Used to measure how much (or the quantity of) liquid an object can hold.
• Millilitre (ml)
• Litre (l)

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Metric conversions

The different units in the metric system revolve around how many of the base units they equal. For instance, measuring distance involves thinking about how many metres away something is. Remember, there are different words with different prefixes to express how many metres you’re working with. This is the case for units both larger and smaller than the base unit.

The tables below show units both larger and smaller than the starter base unit. As you look to the right, the units get smaller, and as you look to the left, the units get larger. Note the placement of decimals and the number of zeros attached to each value.

 1000 100 10 Base Unit .1 .01 .001 kilometre hectometre decametre Metre decimetre centimetre millimetre
 1000 100 10 Base Unit .1 .01 .001 kilogram hectogram decagram Gram decigram centigram milligram
 1000 100 10 Base Unit .1 .01 .001 kilolitre hectolitre decalitre Litre decilitre centilitre millilitre

As you can see, moving on to the next unit is just a matter of moving the decimal to the left or right. One decametre is equal to 10 metres, a hectometre is equal to 100 metres, and a kilometre is equal to 1000 metres. Notice that each new unit is the product of multiplying by 10.

The same is true for division when looking at units smaller than a metre. One decimetre is 1/10 or .1 of a metre, a centimetre is 1/100 or .01 of a metre, and a millimetre is 1/1000 or .001 of a metre.

Generally speaking, people seldom use measurements with the hecto, deca, and deci prefixes in everyday situations. Regardless, these are good to know in order to understand the steps in metric units.

The metric system in the real world

The metric system is becoming more and more common. You likely see and use the metric system in all sorts of situations:

• Serving sizes on various food products
• Measurements in recipes (especially those written in/from other countries)
• Athletic competitions such as track and field
• Getting measurements for certain types of clothes

There’s a reason why most of the world uses the metric system:

• Simplicity — Conversions in the metric system are simply a matter of multiplying or dividing by 10. This ease allows for quicker calculations and less room for error.
• Universality — With so much of the world using the metric, professionals and scientists can share data easily without needing to convert from one measurement system to another.
• Flexibility — Since all the units in the metric system use the same prefixes—regardless of what you are measuring—the system easily adapts to your every measuring need.

Let’s practise together!

1. How many centimetres are in 5 metres?

A centimetre is 1/100 of a metre, which means each metre equals 100 centimetres. Multiply that by 5 and you get 500 centimetres.

2. Convert 3.5 litres into millilitres.

3,500 millilitres. A litre is equal to 1,000 millilitres, so you have at least 3,000 millilitres in 3.5 litres. The .5 decimal value indicates that there is an additional half a litre to account for. Half of 1,000 is 500, so our total is 3,500 millilitres.

3. What is smaller, 100 centimetres or 1/1000 of a kilometre?

This is the same amount, 1 metre. 100 centimetres equals 1 metre, and 1,000 metres equals 1 kilometre.

Ready to give it a go?

Metric is an easy-to-use system once you know the prefixes. Refer back to the tables from earlier to help you remember what the units are called.

Practice problems

A decimetre.

Centimetre is smaller.

Metres measure length, grams measure weight, and litres measure volume.

A decimetre

How did we get here?

1. 1/10 of a metre means we are dividing 1 metre by 10, once.
2. One division by 10 is one spot to the right on the table, which brings you to decimere

1000

How did we get here?

The prefix kilo means thousand, so a kilogram is 1,000 grams.

1.5 litres

How did we get here?

1. 1,000 millilitres equals 1 litre, so we are left with 500 millilitres.
2. 500 millilitres is half of 1,000, so you can express that as .5 litres.
3. Put those together and you have 1.5 litres.

Centimetre is smaller

How did we get here?

1. A centimetre is 1/100 of a metre while a hectometre is 100 metres.
2. This means that a centimetre is much smaller than a hectometre.

Metres measure length, grams measure weight, and litres measure volume.

The metric system is based on base units like metres and litres. Larger units equal each unit multiplied by ten. Smaller units result from dividing units by 10. The imperial system uses units with historical origins dating all the way back to ancient Rome.

Make recipes in metric, think about distances in kilometres, and pay attention to the metric labels on the foods you buy.

Lesson credits

Taylor Hartley

Taylor Hartley is an author and an English teacher. When she's not writing, you can find her on the rowing machine or lost in a good novel.

Jill Padfield has 7 years of experience teaching mathematics. She is currently working as a Business Analyst, working to improve services for Veterans while earning a masters degree in business administration.

Taylor Hartley

Taylor Hartley is an author and an English teacher. When she's not writing, you can find her on the rowing machine or lost in a good novel.

Jill Padfield has 7 years of experience teaching mathematics. She is currently working as a Business Analyst, working to improve services for Veterans while earning a masters degree in business administration.

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