BC to AD Calculator

Created by Julia Żuławińska
Reviewed by Steven Wooding
Last updated: Nov 02, 2022

BC to AD calculator can quickly tell you the time difference between a BC and AD year. Read on to learn what BC and AD stand for and how to tell how many years ago was any BC date. You can also learn about the differences between BC, BCE, AD, and CE.

If you want to find the time difference between dates of this era, go to date to date calculator.

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, people decided that the birth of Christ would be a reference point to track time, and came up with these abbreviations.

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.

💡 Whenever writing BC/BCE dates, you write the abbreviation after a date. For example, 150 BCE or 30 BC. When you write about the current era, the abbreviation should be at the beginning; AD 2022 or CE 1991.

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 ago was 1400 BC, 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.

🙋 Our time calculator is our most diverse tool for calculations with time. Check it out next!


How many years are in a century?

There are 100 years in a century. Now, we are living in the 21st century. It started in 2001 and will finish at the end of 2100.

How long ago was 100 BC in years?

100 BC was 2121 years ago. To find how long ago any BC date is, you need to add that date to the current year and subtract one. So, in this example, 100 plus 2022 minus one equals 2121.

How many years ago was 206 BCE?

206 BCE was 2227 years ago. To find how many years ago was any BC/BCE year, you need to add to it the current year and subtract one. You can also use our BC to AD calculator.

How to calculate years between BC and AD?

To calculate the time difference between BC and AD dates, you need to:

  1. Add the two dates together.
  2. Subtract one.
  3. That's all – you have your result. Check if it's correct with Omni's BC to AD calculator.
Julia Żuławińska
Type year:
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