Century Calculator

A century is a period of exactly 100 years. Centuries are commonly used in history and chronology to group years into meaningful time blocks. For example, the years 1901 through 2000 form the 20th century.

To find the century for any year, subtract 1 from the year, divide by 100, take the integer (whole number) part, then add 1. For example, for 1987: (1987 − 1) ÷ 100 = 19.86, integer part = 19, plus 1 = 20th century.

Because there is no year 0 in the traditional calendar system — years go from 1 BC directly to 1 AD. This means the 1st century ran from year 1 to year 100, and every subsequent century starts on a year ending in 1. So the 21st century began on January 1, 2001.

For BC years, enter a negative number (e.g. -44 for 44 BC). The calculator determines the correct century for BCE dates. Note that year 0 is skipped in traditional reckoning, so -1 represents 1 BC.

Roman numerals are frequently used to express centuries in historical, academic, and artistic contexts. For example, the 19th century is written as XIX, and the 21st century is XXI. This calculator optionally displays the century in Roman numeral format.

A century always contains exactly 100 years. It typically includes 24 or 25 leap years depending on which years fall within it, since leap years occur roughly every 4 years (with exceptions for century years not divisible by 400).

A century spans 100 years, while a millennium spans 1,000 years — meaning one millennium equals exactly 10 centuries. For example, the 2nd millennium AD ran from 1001 to 2000, covering the 11th through 20th centuries.

The century is determined solely by the year component of any date. Simply enter the year from your date into this calculator, and it will return the correct century regardless of the month or day.