Century of a Year

The calculation of the centuries follows these principles :

The first century starts the 1st january of year 1 (there is no year 0 in any gregorian or julian calendar).

The second century starts 100 years later so the first january 101 and so on, the 21st century starts the 1st of january 2001 (as the 3rd millennium), so currently the humanity lives in the 21st century.

Before Christ, the principle is reversed, the 1st century before Christ starts the 1st january -100 and ends the 31 december -1, included.

Take the value in years and divide by 100.

Example: For 250 years, do 250/100 = 2.5 so 250 years is equal to 2.5 centuries

Between year 1 and year 1000 included, it is the first millennium. Between the year 1001 and the year 2000 is the second millennium. Between the year 2001 and the year 3000 is the third millennium (started on January 1, 2001 and will end on December 31, 3000) so currently we are in the 3rd millennium.

We are currently in the 21th century which began on January 1, 2001 and that will end on December 31, 2100.

Add 1 to the first 2 digits (on the left) of the year of birth, unless it is a year that ends in 00.

Example: 1999 => 19 + 1 = 20 => 20th century

Example: 2000 => 20 => 20th century

Example: 2001 => 20 + 1 = 21 => 21st century

There was no century 0, so on January 1st of year 1 the first century began. 100 years later, on January 1 of the year 101 began the second century and 100 years later, on the 1st of January of the year 201 began the third century. There is therefore a relation between the digit of hundreds of a date and the number of the century. The number of the century is equal to the number of hundreds increased by 1. (Except for the years ending with 00).

In order to replace the expressions before Jesus Christ and after Jesus Christ, it is more and more common to use before our era, or before common era (AEC) for negative years and likewise common era (EC) for recent positive years.

Use the dCode function to convert centuries in roman numerals.