Unit of Length

Introduction:

When we try to understand what is the basic unit of length, well, there isn’t a standard unit of length. This is because there are several measurement methods or systems that are currently used around the world. Further, there are several systems that specify their own basic unit.

However, the most common units that are used presently are U.S. customary units and the metric units, including SI and non-SI units. Additionally, British Imperial units are also still used in some countries. Let’s look at some of the units in detail.

Table of Contents

What is the SI Unit of Length?

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

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

Some of the other units also include:

  • kilometres
  • nanometre
  • millimetres
  • centimetres
  • metres
  • decimetres

To get an idea of how big the metric units are, look at the table below

Metric
Example
Millimetre The thickness of a plastic id card or a credit card is about a millimetre thick
Centimetre A fingernail is about a centimetre wide
Metre A guitar is a metre long
Kilometre The distance between cities is measured in kilometres

Other Non-SI Length Units

If you look at the Imperial and U.S. customary systems, then the basic unit of length is the yard. Some of the 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)

You may also want to check out these topics given below!

Frequently Asked Questions – FAQs

Q1

What is the SI unit of Length?

The SI unit of length is a metre.
Q2

Define Metre.

“The length of the path travelled by light in a vacuum within 1⁄299792458 seconds.”
Q3

What is the unit of Length in the U.S. customary systems?

In U.S. customary systems the basic unit of length is the yard.
Q4

What are the other units of Length?

The other units of length are :

  • kilometres
  • nanometres
  • millimetres
  • centimetres
  • metres
  • decimetres

To learn about various interesting science topics, subscribe to the BYJU’S app!

Test your knowledge on Unit Of Length

Comments

Leave a Comment

Your Mobile number and Email id will not be published.

*

*