Millimetres, Centimetres, Metres and Kilometres
Basics on the topic Millimetres, Centimetres, Metres and Kilometres
Metric Units – Kilometres, Metres, Centimetres and Millimetres
What are kilometres, metres, centimetres and millimetres?
If you want to measure the length of something, you need to label length using units of measurement. There are different units in which we can indicate the length of something. What are centimetres, metres, kilometres, and millimetres? They are all metric units of measurements for length! From smallest to largest measurement, we have millimetres, centimetres, metres, and kilometres.
Metric Measurement Relationship
How many metres are in a kilometre? How big is a metre in centimetres? These are questions you might find yourself asking. Millimetres, centimetres, metres and kilometre are all metric measurements of length! Let’s find out more about how they compare to each other. One unit on the left column equals the amount of the relatively smaller unit of measurement on the right.
Larger metric unit  Smaller metric unit 

1 centimeter  10 millimeters 
1 meter  100 centimeters 
1 kilometer  1,000 meters 
Look at the above chart. Are kilometres bigger than metres? Yes, we can see that from the chart. We can also see that metres are bigger than centimetres and centimetres and bigger than millimetres.
How do you relate metres (m) to kilometres (km)? Each unit of measurement relates to the others, because you have so many of one, in a number of the other.
For example, let’s look at millimetres first. There is one million millimetres in a kilometre, one thousand millimetres in one metre, and one hundred millimetres in a centimetre.
Now let’s look at centimetres. There is one hundred thousand centimetres in a kilometre, and one hundred centimetres in a metre. Let’s look at examples from the real world for each metric unit of measurement.
Now let’s look at metres. There is one thousand metres in a kilometre.
Metric Units – Examples
A millimetre is roughly the size of the thickness of a paper clip.
A centimetre is roughly the length of a bug like this one.
A metre is roughly the length of a guitar.
A kilometre is roughly the distance between the support towers on the Golden Gate Bridge in San Francisco, USA.
Metric Units – Summary
The metric units for measuring length are millimeters, centimeters, meters, and kilometers. These units describe the length of objects from very small objects (measured in millimeters) to very large objects (measured in kilometers).
They are related because you can convert one to the other! Below is an overview of these four metric units of measurement.
They are related because you can convert one to the other! Below can find interactive exercises, worksheets and more activities concerning millimetres, centimetres, metres and kilometres.
Frequently Asked Questions – Metric Units
Transcript Millimetres, Centimetres, Metres and Kilometres
"If you call right now, you will get TWO measuring kits for the price of ONE, delivered immediately!" "I can't believe people fall for that, can you Zuri?"
"I'll take two measuring kits, please!"
"Well, you've purchased it now, might as well take a look."
Let's join Zuri and Freddie as they learn all about Millimetres, Centimetres, Metres, and Kilometres.
Metric measurements, or units, of length that we use are kilometres, metres, centimetres, and millimetres.
A millimetre is a small measure of length and is represented by the abbreviation
"Order now to get my Weighted Wonders kit!" "No Zuri, please don't..." "I'll take one of the Weighted Wonders kits please!"
Millimetres, Centimetres, Metres and Kilometres exercise

Abbreviating units of measure.
HintsAbbreviations usually include the first letter of the word.
All the abbreviations will have the letter m, which would represent "metres" because it is the metric system.
Am abbreviation is a shortened form of a word or phrase. For example, United Kingdom can be abbreviated to UK.
Solution millimetres: mm
 centimetres: cm
 metres: m
 kilometres: km

Ordering metric units.
HintsThe smallest unit of measurement goes at the top.
The largest unit of measurement goes at the bottom.
There are 1,000 metres in a kilometre.
SolutionMetric units of length from smallest to largest:
 millimetres (mm)
 centimetres (cm)
 metres (m)
 kilometres (km)

Estimate the length of the objects.
HintsSmaller objects need to be measured using a smaller unit of measurement.
This image is showing the distance between between places on a map.
Think about which object is the smallest. This would be measured in millimetres.
Use this comparison chart to help you decide on the units used to measure each item.
Solution The pencil end is about 5 mm.
 The crayon is about 5 cm.
 The fence is about 5 m.
 The distance from the two locations on the map is about 5 km.

Complete the sentences about metric units.
HintsPeople describe a century as 100 years. Does this help answer the question about cent?
Use this comparison chart to help you complete the statements above.
Which metric unit has a part that sounds similar to million? Centimetre, millimetre or kilometre?
Solution There are a million millimetres in one kilometre.
 The word centimetre stems from the word century meaning 100.
 One kilometre is equal to 1,000 metres.
 Kilometres are the largest metric unit for measuring length.
 The word kilo means 1,000.

Which units would measure each object?
HintsThe smallest item is the beetle and the largest item is the bridge.
Use this comparison chart to help you decide on the units used to measure each item.
You should use all four colours in the task. Each item should have a different colour assigned.
SolutionThe items would be measured using the following units:
 the beetle: yellow (millimetres)
 the paperclip: green (centimetres)
 the guitar: blue (metres)
 the bridge: violet (kilometres)

Convert the metric units of measurement.
HintsUse these conversions to help:
 1,000 mm = 1 m
 100 cm = 1 m
 1,000 m = 1 km
We know there are 100 cm in 1 metre. When we look at 300 cm, we have multiplied 100 by 3, so we also mulitply 1 m by 3 to find the equivalent in metres.
There are 10 mm in 1 cm. We multiply 1 cm by 100 to get a metre, so to find the equivalent in mm, we multiply 10 by 100.
Solution 1 km = 1 mm is not correct ❌ because 1 km is 1 million millimeters.
 1,000 m = 1 km is correct ✅.
 100 cm = 1 m is correct ✅.
 10 mm = 1 m is not correct ❌ because 10 mm is equal to 1 centimetre.
 2 km = 2,000 m is correct ✅.
 3 m = 300 cm is correct ✅.