When learning about history, you’ll often see events described as taking place in a particular century, but the way centuries are numbered can be downright confusing. For example, the Vikings invaded England in the 8th century, the First Crusade took place in the 11th century, and the American Civil War was fought in the 19th century. Jumping to the future, Star Trek: Picard takes place in the late 24th and early 25th centuries. That’s great, but what years are we really talking about here?
This simple guide will tell you exactly what a century is, how centuries are numbered, and how to tell which century a year is in.
What is a Century?
A century is a period of 100 years. A 100th anniversary of something—like a business—is known as a centenary or centennial. A person who is 100 years old is a centenarian.
Now, a century can technically be any consecutive 100 years. But historians use centuries as a handy tool to divide time into nice, neat 100-year blocks that have very specific years.
How are Centuries Numbered?
The first century of our current era begins with the year 1. The concept of “zero” wasn’t a thing back when our dating system was devised, so there is no year 0.
Therefore, the 1st century refers to the years 1–100.
Following this logic:
2nd century = 101–200
3rd century = 201–300
8th century = 701–800
13th century = 1201–1300
19th century = 1801–1900
20th century = 1901–2000
21st century = 2001–2100
You’ll also see people refer to a century using the “hundreds.” For example, the years 700–799 are often called the 700s, and years 1900–1999 are known as the 1900s. While this is correct, be careful not to confuse the “hundreds” form with the specific century.
While the years 700–799 are the 700s, only the year 700 is in the 7th century. The years 701–799 are in the 8th century.
Similarly, the years 1900–1999 are the 1900s, but only the year 1900 belongs to the 19th century. The years 1901–1999 are not in the 19th century; they’re in the 20th century.
What About BCE/BC?
For all of my ancient history buffs out there, you may be wondering: what about the BCE/BC centuries? Basically, they follow the same 100-year pattern as the centuries after year 1 (which we call CE/AD). Just make sure to differentiate them by stating BCE or BC.
Here are some examples:
1st century BCE = 100–1 BCE
2nd century BCE = 200–101 BCE
5th century BCE = 500–401 BCE
13th century BCE = 1300–1201 BCE
19th century BCE = 1900–1801 BCE
35th century BCE = 3500–3401 BCE
The major difference is that we count BCE/BC dates backward from year 1. This means that larger numbers are older and occurred before smaller ones. For example, 200 BCE came before 45 BCE.
For a lowdown on the difference between BCE/BC and CE/AD, see WTF are BCE/CE and BC/AD?
How Can You Tell Which Century a Year Is In?
Now that we have the basics down, we can figure out which century a specific year is in. There are a couple of easy tricks to figure it out so you don’t have to memorize the years in every century.
4 Digit Years
If the year has 4 digits, then take the first two digits and add 1 to get the number of the century.
Let’s take the year 2026 as an example.
- We’ll drop the “26” and keep the “20.”
- Add 1 to 20: 20+1=21
- Voilà, 2026 is in the 21st century.
Quiz yourself with the following years. Click the + below to reveal the answers and a fun fact.
1066 is in the 11th century.
In 1066, William the Conqueror, Duke of Normandy, led the Norman conquest and invaded England. He became the first Norman King of England.
1517 is in the 16th century.
On October 31, 1517, Martin Luther posted his 95 Theses on the door of the Castle Church in Wittenberg. The Theses criticized the Roman Catholic Church—especially indulgences—and sparked the birth of the Protestant Reformation.
1776 is in the 18th century.
On July 4, 1776, Congress adopted the Declaration of Independence and officially broke up with King George III and Britain. The 13 North American colonies thus became the United States of America.
1945 is in the 20th century.
World War II ended in 1945. On May 8, 1945, Germany officially surrendered. The war continued in the Pacific until Japan agreed to unconditional surrender on September 2, 1945.
3 Digit Years
If the year has only 3 digits, take the first digit and add 1 to get the number of the century.
We’ll use the year 476 as an example.
- Drop the “76” and keep the “4.”
- Add 1 to 4: 4+1=5
- 476 is in the 5th century.
Use your expertise to name the century for the following years. Click the + below to reveal the answers and a fun fact.
117 is in the 2nd century.
In August 117, Roman Emperor Trajan died at Selinus, in modern-day Türkiye. Hadrian succeeded him.
330 is in the 4th century.
On May 11, 330, Constantinople officially became the Roman Empire’s new capital. Constantinople is now modern-day Istanbul, Türkiye.
525 is in the 6th century.
In 525, the Christian monk Dionysius Exiguus of Scythia Minor devised the AD (Anno Domini/in the year of our lord) dating system.
793 is in the 8th century.
In June 793, Vikings raided the Lindisfarne Monastery off England’s northeastern coast. The monastery housed the remains of Saint Cuthbert.
Years Ending with 00
This is the only case that might trip you up, so it’s important to remember this rule. When a year ends with “00,” like 300, don’t add 1 to any digits. These years always mark the end of a specific century and therefore belong to that century. So, 300 is the final year in the 3rd century.
Test your knowledge with the following years. Click the + to reveal the answers and a fun fact.
800 is in the 8th century.
Pope Leo III crowned Charlemagne (King of the Franks) Holy Roman Emperor on December 25, 800.
1500 is in the 15th century.
Portuguese explorer Pedro Álvares Cabral is credited with “discovering” Brazil on April 22, 1500. However, historians believe Spanish explorer Vicente Yáñez Pinzón got there first, on January 26, 1500.
2000 is in the 20th century.
2000 was the start of a new millennium and was known as Y2K. We all thought the world was going to end. Yet here we all are.
Now that you are an expert in the century numbering system, you know Captain Kirk took command of the USS Enterprise in 2265, which is the 23rd century.
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