A century is a measure of time. 1 century spans a period of 100 years. Although a century can refer to any period of 100 years (e.g. a person who is 1 century old is 100 years old), in everyday use the term century usually refers to a specific period of 100 years using the Gregorian calendar. For example, the 20th century began on January 1, 1901 and ended on December 31, 2000. The 21st century began on January 1, 2001, and ended on December 31, 2001, and so on. Any calendar year(s) from 1901-2000 is considered to be part of the 20th century. Centuries are often used when referencing points in history (13th century, 18th century, 20th century, etc.) in the Gregorian calendar.

Converting centuries

A century is a such a long period of time that it can be difficult to grasp conceptually. Looking at a century in terms of periods of time we are far more accustomed to can help us gain an understanding of its scale. Below are some conversions between a century and other commonly used measurements of time.

This should give us a better idea of the scale of a century. It is also worth noting that it would be difficult to discuss history or longer periods of time if we always had to talk about time in terms of seconds. Being able to use larger measurements of time (such as centuries) allows us to effectively communicate. This is one reason that learning about various units of measurement is important: it enables us to choose the appropriate unit for the given context.


Convert the following measurements of time into centuries.

1. 1 year:

1/100 = 0.01 centuries

2. 438,300 hours:

438,300 / 876,600 = 1/2 = 0.5 centuries

3. 1000 months:

1000 / 1200 = 5/6 = 0.833 centuries

Did you know?

The United States has been a country for around two and a half centuries. The oldest country in the world is China, which has a recorded history of about 30 centuries.

"Centennial" is a term related to century that means the hundredth anniverary, or the celebration of the hundredth anniversary of an event. Since the Declaration of Independence was signed in 1776, its centennial occurred in 1876. Similarly its bicentennial was celebrated in 1976.