What Do BC and AD Stand for? Dates in History

, Staff Editor
Updated January 14, 2022
timeline BC (BCE) versus AD (CE)
    timeline BC (BCE) versus AD (CE)
    baby Jesus: Guzaliia Filimonova / iStock / Getty Images Plus , Jerusalem: grkatz / iStock / Getty Images Plus

Once you learn what BC and AD mean in terms of historical timelines, it’s easy to see the difference between the abbreviations BC and AD. Explore the history of these time abbreviations and how they relate to the abbreviations BCE and CE.

What BC and AD Stand For

Understanding where BC and AD came from and why they’re used can help make their meanings clear. Together, they form what is known as the Christian Era.

BC Abbreviation Meaning

The abbreviation BC stands for “Before Christ.” It refers to all time before the theoretical birth of Jesus Christ.

AD Abbreviation Meaning

The abbreviation AD stands for “Anno Domini” in Latin. In English, this means “in the year of our Lord.” This abbreviation refers to all time after the theoretical birth of Jesus Christ.


History of BC and AD Abbreviations

An Italian monk named Dionysius Exiguus is believed to be the person who came up with BC and AD, or the Christian Era, in the AD 500s sometime after AD 525. These abbreviations and this method of calculating time came out of an argument about how to calculate Easter.

Dionysius calculated the birth of Christ as being in the year 753 AUC (ab urbe condita, Latin for “from the foundation of the city of Rome”). He then made the year Christ was born AD 1 and all time before that started from 1 BC. Although his calculations have been questioned for centuries, Dionysius’ system has stuck. It gained widespread use in the 11th century.

Modern Use of BC and AD

BC and AD are still commonly used around the world as time designations because they are habitual and the accepted abbreviations of Christians. Scholarly guidelines from the 21st century encourage the use of BCE and CE over BC and AD because the newer abbreviations are more inclusive.


BC and AD Timelines

AD time starts when BC time ends, but there is no year 0. So, BC starts in the year 1 BC and AD starts in the year AD 1.

Proper Use of BC and AD Abbreviations

You may see variations of the abbreviations BC and AD used in a variety of settings. In general, these abbreviations are written without periods, so not B.C. and A.D.

When writing a BC date, you put the BC after the year. When writing an AD date, you put the AD before the year.

BCE and CE Eras

In attempts to make historical eras non-religious, the abbreviations BCE and CE were created to replace BC and AD respectively in the 17th century.

BCE and CE History

Historians and scholars who were not Christians used the BCE and CE abbreviations to communicate with religious groups about history. The BCE era is exactly equivalent to the BC era and the CE era is exactly equivalent to the AD era to respect religious beliefs, yet make history inclusive.


BCE Abbreviation Meaning

The abbreviation BCE stands for “Before the Common Era.” This refers to all time before the theoretical birth of Christ. For some, BC is now called BCE, but they refer to the same timeframe.

CE Abbreviation Meaning

The abbreviation CE stands for “Common Era.” This refers to all time after the theoretical birth of Christ. For some, AD is now called CE, but they refer to the same time.

Proper Use of BCE and CE

The abbreviations BCE and CE are generally written without any periods between the letters, so not B.C.E. or C.E. The letters BCE and CE go after the year when you are writing a date.

What Year Is It?

While the definitions and meanings of abbreviations like BC and AD are simple, calculating time and historical eras isn’t so easy. Continue exploring years, eras, and dates by seeing if you write dates correctly.