What Do BC and AD Stand For? | Meaning & Use
BC stands for “before Christ” and refers to years before Jesus Christ’s estimated birth, starting with 1 BC and counting backward. AD stands for “anno Domini,” which is Medieval Latin for “in the year of the Lord” and denotes the years after Jesus’s birth. It starts with year 1 and extends to the current day.
| BC | AD |
|---|---|
| The first recorded Olympic Games were held in Olympia, Greece, in 776 BC. | In AD 476, the Western Roman Empire fell, marking the end of ancient Rome. |
| The Roman Republic was established in 509 BC. | In AD 622, the Prophet Muhammad migrated from Mecca to Medina, marking the beginning of the Islamic calendar. |
| Alexander the Great conquered Egypt in 332 BC. | In AD 800, Charlemagne was crowned Emperor of the Romans by Pope Leo III. |
What does BC stand for?
BC stands for before Christ and is used to denote years before the assumed birth of Jesus Christ, the messianic figure of Christianity.
BC counts backward from 1 BC. For example, if you’re reading about a historical event that occurred in 25 BC, that means it happened 25 years before the birth of Jesus. While BC dates can theoretically extend indefinitely into the past, they’re rarely used beyond 10,000 BC except in scientific contexts.
BC dates are always written with “BC” placed after the year (e.g., 1200 BC). This is important to remember for clarity, as it conveys the meaning “1200 years before Christ,” which is why “BC 1200” or “before Christ 1200 years” is incorrect.
Buddha was born in 563 BC.
The construction of Stonehenge began around 3000 BC.
What does AD stand for?
“AD” stands for “anno Domini,” which is Medieval Latin for “in the year of the Lord” (though it’s commonly translated to “in the year of our Lord”). It’s used to designate years and historical eras after the estimated birth of Jesus Christ.
“AD” begins with year 1 and extends to the present day. For instance, the year 2024 is technically the year AD 2024, meaning it’s 2,024 years after the birth of Jesus Christ.
The formatting of AD dates is more flexible than that of BC dates. Traditionally, AD dates are written with “AD” preceding the year (e.g., “AD 60”), but it’s also acceptable to place it after (e.g., “60 AD”). Moreover, “AD” can follow a specific century or millennium (e.g., the third century AD).
In modern usage, especially for dates after the first century, “AD” is often omitted, though its usage is technically correct and can add clarity, especially in historical writing.
Mount Vesuvius erupted in AD 79, destroying Pompeii and Herculaneum.
It is believed the Gospel of Luke was written around AD 80–85.
BC vs AD history
The AD chronological system, which counts years after the birth of Jesus, was created in AD 525 by the monk Dionysius Exiguus. However, it didn’t become widely used until the eighth or ninth century, beginning in England before spreading to France and Italy. The aim was to center the Christian timeline on Jesus rather than Roman emperors.
The “BC” designation developed more slowly, going through various iterations and formulations, before it gained consistency in the 17th and 18th centuries. Historians like Bede and Dionysius Petavius made significant contributions to its development.
It’s important to note that while the BC/AD system is widely used, it’s not universal. Some cultures rely on different calendars, and academia often prefers using BCE (before the Common Era) and CE (Common Era) notation, as it is religiously neutral.
Frequently asked questions about BC vs AD
- Is BC older than AD?
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Yes, years labeled “BC” (e.g., 700 BC) are older than dates labeled “AD” (e.g., AD 900).
Keep in mind that BC stands for before Christ and refers to years that happened before the birth of Jesus Christ. AD stands for anno Domini, which means “in the year of the Lord” in Latin, and refers to years after the birth of Jesus Christ.
- How do you format BC dates?
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BC dates are typically formatted by writing the year followed by “BC” (e.g., 550 BC). The BC era starts with 1 BC and goes backward until 10,000 BC.
“BC” always comes after the year. For example, 700 BC essentially means “700 [years] before Christ [was born];” therefore, “BC 700” would be incorrect.
- How do you format AD dates?
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AD dates are traditionally formatted by writing “AD” before the year (e.g., AD 400) but can sometimes be found with “AD” placed after the year (e.g., 400 AD).
“AD” indicates years after the assumed birth of Jesus Christ, starting with AD 1, all the way until the present day.
However, in modern usage, “AD” is often omitted for dates after the first century, especially in informal contexts. For example, the use of “AD” is not necessary when referring to the year 2024.
