The BC to AD calculator allows you to quickly determine the number of years between a date in BC and one in AD. In this guide, you’ll learn what the terms BC and AD mean, how to calculate how many years have passed since a BC date, and how these systems compare to BCE and CE.
If you’re looking to measure the time span between two dates within the same era, you can use a date-to-date calculator instead.
What Do BC and AD Mean?
BC is short for Before Christ, while AD comes from the Latin phrase anno domini, meaning “in the year of our Lord.” During the Middle Ages in Europe, the birth of Christ was chosen as a central reference point for measuring time, and these labels gradually became widely used across many regions.
Today, you’ll often see BCE and CE used in place of BC and AD. This alternative avoids religious references and is considered more neutral and inclusive. BCE stands for Before Common Era and corresponds to BC, while CE, meaning Common Era, serves the same purpose as AD.

