What does BC and AD stand for?

BC stands for Before Christ. AD stands for "anno domini", which translates to "Year of our Lord." In the Middle Ages in Europe, people decided that the birth of Christ would be the reference point to track time, and came up with these abbreviations that gradually became popular in many parts of the world.

More often, you can see people use the abbreviations BCE and CE instead of BC and AD. That's because, for some people, the connotation of Christianity with BC and AD is problematic. The new version is more universal. BCE stands for "Before Common Era" and is a replacement for BC. As you might guess, CE stands for "Common Era" and replaces AD.

BC and AD timeline

To find the time difference between years in BC and AD, you need to add them together and subtract one:

Year Difference = BC year + AD year - 1

For example, to learn how many years are between 1400 BC and 2022 AD, you need to apply the formula (or just use our BC to AD calculator):

Year Difference = 1400 + 2022 - 1 = 3421

You need to subtract one because there is no year zero on a BC and AD timeline. As soon as 1 BC ends, AD 1 starts. So between the first of January 1 BC and the first of January AD 1, it's precisely one year.

Example

Understanding BC to AD Calculations

BC (Before Christ) and AD (Anno Domini) calculations are essential in history, archaeology, and timeline analysis. These calculations help determine the number of years between historical events and track historical timelines.

The key concepts of BC to AD calculations include:

Years Between BC and AD: Since there is no year 0, transitioning from BC to AD requires adding both values.
Finding the Century: Each century consists of 100 years, counted forward in AD and backward in BC.
Historical Timeline Analysis: Used in history and archaeology to calculate gaps between events.

Calculating Years Between BC and AD

To determine the number of years between a BC year and an AD year:

Add the absolute value of the BC year to the AD year.

Example: From 200 BC to 300 AD: \( 200 + 300 = 500 \) years.

Finding the Year Difference

To find the difference between two years across BC and AD:

If both years are BC, subtract the earlier year from the later year.
If one year is BC and the other is AD, add both values.

Example: From 50 BC to 150 AD: \( 50 + 150 = 200 \) years.

Determining the Century

To determine which century a BC or AD year belongs to:

Divide the year by 100 and round up.
For BC years, centuries count backward.

Example: Year 350 BC is in the 4th century BC, Year 2023 AD is in the 21st century AD.

Converting BC to AD

To convert BC years to an equivalent AD difference:

BC years are counted negatively on a timeline.
To measure the full span, shift the value to the AD scale.

Example: 500 BC is 500 years before AD 1.

Real-life Applications of BC to AD Calculations

These calculations are useful in various fields, such as:

Tracking historical timelines and archaeological findings.
Determining time gaps between ancient civilizations and modern events.
Calculating historical trends in climate, culture, and technology.

Common Operations in BC to AD Calculations

When performing calculations, the following operations are common:

Adding or subtracting years to determine historical periods.
Using century divisions to categorize events.
Tracking major historical transitions across BC and AD.

Example: The time span from Alexander the Great’s death (323 BC) to the fall of the Roman Empire (476 AD) is \( 323 + 476 = 799 \) years.

BC to AD Calculation Examples Table
Calculation Type	Description	Steps to Calculate	Example
Years Between BC and AD	Calculate the number of years between a BC year and an AD year.	Add the absolute value of the BC year to the AD year.	200 BC to 300 AD: \( 200 + 300 = 500 \) years
Finding the Year Difference	Find the difference between two years across BC and AD.	If both years are BC, subtract the earlier year from the later year. If one year is BC and the other is AD, add both values.	50 BC to 150 AD: \( 50 + 150 = 200 \) years
Finding the Century	Determine the century a BC or AD year belongs to.	Divide the year by 100 and round up. For BC years, centuries count backward.	Year 350 BC is in the 4th century BC, Year 2023 AD is in the 21st century AD.
Converting BC to AD	Find the equivalent positive year difference.	BC years are negative in timeline calculations. To convert to AD, shift to a positive scale.	500 BC to present: 500 years before AD 1
Historical Timeline Calculations	Finding the time span between events.	For events spanning BC to AD, add the years. For events within the same era, subtract normally.	Alexander the Great (323 BC) to the fall of Rome (476 AD): \( 323 + 476 = 799 \) years