What Is Century?
A century is a unit used to count long periods of time. One century is exactly 100 years. People use centuries to talk about history, big changes, and different time periods.
Definition
A century is a period of 100 years in a row.
For example, if something lasts from the year 2000 to the year 2099, it lasts 100 years, so it is one century long.
Centuries are often used to group years in history. When people say the “20th century”, they mean the years from 1901 to 2000. When they say the “21st century”, they mean the years from 2001 to 2100.
History / Origin
The word “century” comes from the Latin word “centum” which means “one hundred”. Long ago, people who spoke Latin used this word for groups of one hundred of anything, such as one hundred soldiers.
Over time, the word began to be used in many European languages to mean 100 years. Historians and writers liked using centuries because they made it easy to divide history into large, clear blocks of time.
Today, the idea of centuries is common in schools, books, timelines, and museums all around the world.
Symbol & Abbreviation
The word “century” is usually written in full in normal writing, but there are a few short forms:
- c. or ca. sometimes means “around this century” or “about this year” in history writing. For example, “c. 5th century”.
- cent. is sometimes used as a short form for “century” in notes and tables.
There is no single official symbol like there is for seconds (s) or meters (m). Most of the time, people simply write “century” or “centuries” in full.
Current Use Around the World
Centuries are widely used in:
- History to group events, for example, “in the 18th century” or “during the 19th century”.
- School books to show timelines and big changes over hundreds of years.
- News and media to compare time periods, for example, “the biggest storm in a century”.
- Everyday speech to mean a very long time, for example, “It feels like a century”.
Most countries today use the same idea of centuries based on the years of the Gregorian calendar, which is the main calendar used worldwide.
Example Conversions
Here are some simple conversions using centuries.
- Centuries to years
1 century = 100 years
2 centuries = 200 years
5 centuries = 500 years - Years to centuries
50 years = 0.5 century (half a century)
75 years = 0.75 century
100 years = 1 century
250 years = 2.5 centuries - Centuries to decades
1 decade = 10 years
1 century = 10 decades
3 centuries = 30 decades - Centuries to months
1 year is about 12 months
1 century = 100 years × 12 months = about 1200 months - Centuries to days (using 365.25 days per year to include leap years on average)
1 century ≈ 100 × 365.25 days ≈ 36,525 days
Related Units
Centuries are part of a group of time units. Here are some closely related ones:
- Year the basic unit used for age and dates. 1 year is the time it takes Earth to go around the Sun once.
- Decade 10 years. There are 10 decades in 1 century.
- Millennium 1000 years. There are 10 centuries in 1 millennium.
- Month about one twelfth of a year. Roughly 1200 months in 1 century.
- Day 24 hours. There are about 36,525 days in 1 century.
- Hour, minute, second smaller time units that can also be linked to centuries with large numbers.
FAQs
How many years are in a century
There are exactly 100 years in one century.
When does a new century start
A new century starts in a year that ends with 01, not 00. For example, the 21st century began on January 1, 2001, not in 2000.
What years are in the 20th century
The 20th century covers the years from 1901 to 2000. Even though the year 1900 starts with 19, it is part of the 19th century because counting starts at year 1.
What is half a century
Half a century means 50 years. One quarter of a century means 25 years.
What is a millennium compared to a century
A millennium is 1000 years. One millennium is equal to 10 centuries.
Why do people use centuries in history
Centuries make it easier to talk about long periods of time. Instead of listing many years, people can say things like “in the 15th century” to explain when something happened.
Is a century always exactly the same length
Yes. A century is always defined as 100 calendar years. The number of leap years inside that century may change, but it is still counted as 100 years.