Metric Length

What is the Metric System?

The metric system can be defined as a system of measurement that uses the litre, metre, and gram as base units of metric length (distance), capacity (volume), and weight (mass) respectively.

To measure larger or smaller quantities, we use units derived from the metric units.

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  • The given diagram above shows the arrangement of metric units, which are smaller or bigger than the base unit.

  • The units to the right of the base are lesser than the base unit. As we move to the right, each unit is ten times smaller or one-tenth of the unit to its left. So, the word ‘deci’ means one-tenth of the base unit, ‘centi’ is one-tenth of ‘deci’ or one-hundredth of the base unit and ‘milli’ is one-tenth of ‘centi’ or one-thousandth of the base unit.

  • The units to the left of the base unit are larger than the base unit. As we move to the left side, each unit is 10 times greater than the unit to its right side. So, a ‘deca’ means 10 times of the base unit, ‘hecto’ is ten times of ‘deca’ or hundred times of the base unit and ‘killo’ is ten times of ‘hecto’ or thousand times of the base unit.




Base Unit 










So, the units for metric length, capacity(volume), and  weight (mass) in the metric system are:

Metric Length: Centimeter (cm), Millimeter (mm), Meter (m), Decimeter (dm), and Kilometer (km) are used to measure how wide or long, or tall an object is.

Examples include measuring the thickness or metric length of cloth, a debit card, or distance between 2 cities.

Kilometer (km)


Hectometer (hm)


Decameter (dam)


Meter (m)


Decimeter (dm)


Centimeter (cm)


Millimeter (mm)


Converting Larger Units to Smaller Units

1 centimeter = 10 millimeters

1 meter = 100 centimeters

1 meter = 1,000 millimeters

1 kilometer = 1,000 meters

To Convert bigger units to smaller units we multiply the number of large units by the conversion factor for the appropriate smaller units.

What is the SI Unit of Metric Length?

In the metric system, the SI unit of length is a meter which is defined as follows:

“The metric length of the path that is travelled by light in a vacuum within 1⁄299792458 seconds”.

Some of the other units also include:

  • Kilometres

  • Nanometer

  • Millimetres

  • Centimetres

  • Meters

  • Decimeters

For understanding how big the metric units are, look at the table below:




The thickness of a credit card or a plastic id card is about a millimetre thick


A fingernail is about a centimetre wide


A guitar is a meter long


The distance between cities is measured in kilometres

Other Non-SI Metric Length Units

If we take a look at the Imperial and U.S. customary systems, then the basic unit of metric length is the yard. Some other units include:

  • Thou (1⁄1000 of an inch)

  • Line (1⁄12 of an inch)

  • Inch (25.4 mm)

  • Foot (12 inches, 0.3048 m)

Measure of Metric Lengths

10 millimeters (mm) =

1 centimeter (cm)

10 centimeters (cm) =

1 decimeter (dm) = 100 millimeters

100 centimeter(cm) =

1 meter (m) = 1,000 millimeters

1000 meters (m) =

1 kilometer (km)

The table given below makes Conversion easy:

If You Have This

Do This

To Get This

Millimeters (mm)

Divide by 10 (mm/10)

Centimeter (cm)

Centimeters (cm)

Multiply by 10 (cm * 10)

Millimeters (mm)

Meters (m)

Multiply by 100 (m * 100)

Centimeters (cm)

Centimeters (cm)

Divide by 100 (cm/100)

Meters (m)

Millimeters (mm)

Divide by 1000 (mm/1000)

Meters (m)

Problems to be Solved

Example 1: Convert 5 km to m.

As 1 km = 1000 m

Therefore, 5 km equals 5 × 1000 equals 5000 m.

Fun Facts

  1. A tonne is 1,000 kilograms.

  2. The metric system has its beginnings back in 1670 by a mathematician called Gabriel Mouton.

  3. Since the year 1960s the metric system is known as the "International System of Units" or "SI" (from the French "Système International").

  4. The prefixes of the metric system can be remembered with the help of the mnemonic “King Henry Died of Drinking Cold Milk”.

  5. There are various units greater than the kilo as well. These have prefix mega, giga and tera. A mega is 1000 times of kilo. A giga is thousand times of mega and a tera is a thousand times giga.

FAQs (Frequently Asked Questions)

Question 1. How do you Convert M to CM and MM?

Answer: In this activity, you will convert between metric units of metric length: kilometres, metres, centimetres, and millimetres.

1 km = 1000 m.

1 m = 100 cm.

1 m = 1000 mm.

1 cm = 10 mm.

Question 2. What is the Metric Table for Metric Length?

Answer: Measure of metric Lengths:

10 millimeters (mm) =

1 centimeter (cm)

10 centimeters =

1 decimeter (dm) = 100 millimeters

100 centimeter =

1 meter (m) = 1,000 millimeters

1000 meters =

1 kilometer (km)

Question 3. What are the 7 Basic Units of Measurement in the Metric System?

Answer: The SI system, also called the metric system, is used around the world. There are seven basic units in the SI system, let’s know the units: the meter (m), the kilogram (kg), the second (s), the kelvin (K), the ampere (A), the mole (mol), and the candela (cd).

Question 4. What is the Difference Between SI Units and Metric?

Answer: We can define the metric system as: “A decimal system of units is generally based on the meter as a unit length, the kilogram as a unit mass, and the second as a unit time.”It is commonly referred to as the SI, the full form of SI is Système International and it is also known as the International System of Units.