## Metric Basics

### Introduction

The metric system was first devised in the late 1700s as a means of standardising and simplifying the many weights and measures that existed at that time. Not only did similar sounding measures differ from country to country, but regional or even town-to-town differences were commonplace.

The metric system was rapidly adopted in European countries during the 19th century and has spread to most of the world since. The development of the metric system also became an international effort with significant proposals from British scientists in the 1860s.

### The Base Units

Unit of length: metre
Unit of mass: kilogram
Unit of time: second
Unit of electric current: ampere
Unit of thermodynamic temperature: kelvin
Unit of amount of substance: mole
Unit of luminous intensity: candela

Some of these units might not be familiar to most people, but derived units from those are, such as degrees Celsius derived from kelvins for temperature, electrical power measured in watts derived from amperes, and volume is just length cubed. Time in seconds is universal and everyone should know that there are 60 seconds in 1 minute, and 60 minutes in 1 hour. Some of the derived units use hours, such as velocity (speed) in kilometres per hour. Note also that the term mass is used instead of weight, as weight is not a constant and can vary, and mass is what kilograms actually measure. Weight is a force, which is measured in newtons.

Please look at the pages on this website to explain further the main units and how to use them. Click on your choice here, or view the other links on the site in the menu at the top/bottom of the pages:

Once you know the basic and derived units and their relationships with each other, it is easy to work with them on a daily basis. Once you are familiar with them, it will be much easier to think metric — it’s not rocket science, you do not need a degree to understand the system nor for using it every day, just to know how each unit is used and to think of things that relate to the different metric measurements. It is by far the easiest measurement system devised by mankind to date, and takes very little time to learn.

"...no nation which has adopted the Metric system has failed to derive the greatest benefit from such adoption, or, after adoption has shown any desire to abandon it."
Report from the Select Committee on Weights and Measures (1862).