Is There a Year Zero?

How BC transitions to AD

Grant Piper
2 min readSep 11, 2021
Johannes von Gmunden Calendar (Public domain)

The world counts years with the Anno Domini (AD) system in which the current era is counted from the birth of Jesus Christ. Scholars and secular students have started using Common Era (CE) to replace AD but the numbering is exactly the same. Prior to AD we have Before Christ (BC) or Before Common Era (BCE) which denotes the years leading up to the birth of Christ.

This system begs the question about a year zero. How do we transition from BC to AD?

Year zero AD

At first glance, it would make sense for there to be a year zero in our calendars. The numeral system includes zero. That zero divides negative numbers from positive numbers. Despite that seeming similarity there is no year zero in the Anno Domini system of numbering the years.

The years from the former era and current era simply goes from one to one. The last year of the BC era is 1 BC and the first year of the current era is AD 1. There is no year zero.

There is some debate about whether or not Jesus was born in the year 1 BC or the year AD 1 but his birth is what divides our timeline into the current epochs that we are so familiar with. Despite the debate, everyone jumps from 1 BC to AD 1 with no non-value year in between.

Other year zeroes

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Grant Piper
Grant Piper

Written by Grant Piper

Professional writer. Amateur historian. Husband, father, Christian.