The Birth-Year of Christ according to the Regnal System

The problems and solutions using the Regnal Calendar system for calculating the birth year of Christ.

The following coverage shows that it is not a problem of the Christian religion to identify the year of Christ’s birth. Rather, it demonstrates that an internationally recognized calendar system was not available yet. Mankind was still figuring it out.

The Regnal system is one of the older calendar systems in the annals of human history. The origins are obscure but a natural fit.

It was widely used throughout the ancient Middle East and Mediterranean area and popularized by the Romans.

The problem with the Regnal system of calculating dates is political knowledge. If one does not know when the reign of a leader began or when he died, then this causes dating irregularities. We do not possess all the historical facts today to accurately date anything in history using this system. However, since the New Testament writers reference this system, it becomes an important factor in calculating the birth year of Christ.

The Biblical author Luke used this system on at least two occasions: to describe the birth of Christ under the Governorship of Quirinius,1 and Jesus’ baptism being in the 15th year of the reign of Tiberius.2

This 15th year of Tiberius is critical in many computations, as this is the only solid evidence about the life of Christ that can be accurately measured.

Clement of Alexandria on the birth year of Christ

Clement of Alexandria lived in the later part of the third century. He was a highly educated man in the Greek language and philosophy.

He also used the Regnal system:

“From Julius Caesar, therefore, to the death of Commodus, are two hundred and thirty-six years”.3

Commodus, the Roman emporer in the late 2nd century was his reference point for determining the birth of Christ. Based on his calculations, the death of Commodus was 192 AD, which is consistent with history.4 He then goes on to write, “From the birth of Christ, therefore, to the death of Commodus are, in all, a hundred and ninety-four years.”5 This would make Christ’s birth at 2 BC.

A later editor or Clement himself employed the reign of Augustus to date the birth of Christ stating:

“our Lord was born in the twenty-eighth year when first the census was ordered to be taken in the reign of Augustus.”6

Clement does not indicate what he believed was the start date of Augustus’ reign. It was quite common for some at this time to date Augustus start by the historic war battle of Actium. This event is commonly held to happen at 31 BC. If Clement agreed with this date, then Christ’s birth would have been 3 BC. Perhaps, the first date of 2 BC was common opinion during his era, and 3 BC was the historic Church position.

Clement’s method to calculate a year-date is questionable. For example his date for the destruction of Jerusalem is 6 years off; “the destruction of Jerusalem to the death of Commodus” was “a hundred and twenty-eight years”.7 We know that the destruction of Jerusalem happened in 70 AD, but by his calculations, the destruction would have occurred at 64 AD (192-128=64).

Julius Africanus on fixing the calendar conflicts

Julius Africanus’ life was at its height around 200 AD. He was a traveler and historian whose impact on Eusebius, (who will be described shortly) was immense on this subject.

Frustrated at the inconsistent dating systems available and their diffferences from one region to another, Julius Africanus made the first real attempt to reconcile the Hebrew, Greek, Roman, and Persian histories into one calendar. He came up with a new calendar based on the beginning of Abraham’s life. 8

Eusebius as the golden standard of Regnal dating

More than 40 years later, Eusebius of Caesarea expanded on Africanus’ account. He was well aware that many sources were not satisfactory and there were gaps, but this did not dissuade him from publishing. Eusebius’ work is not available today, except parts in an Armenian text and remnants of it can be found in adaptations in two later writings.

Eusebius lived in the early part of the fourth century and is revered as one of the more credible historians among his many other distinguishing traits. His works are considered important source texts for Christian studies. His calendar references are critically important.

He claimed that Christ was born in the 42nd year of the reign of Caesar Augustus and the 28th year after the Battle of Actium.10

If one assumes that Eusebius’ dates are consistent with standard history, this would make Christ’s birth at 3 BC, or if we use a later Christian document called the Chronological Tables that used Eusebius’ account as the basis, it oddly changes the date to 1 BC/AD.

The Chronological Tables

Firstly, he was copied and expanded by an edition called the Chronological Tables. Copies of this book are still available today. Edited by the ancient fourth-century scholar Jerome, it doesn’t always completely follow Eusebius in the strictest sense. For example, Jerome preserved Eusebius’ introduction, where Eusebius definitively stated, “Christ was born in the 42nd year of the rule of Augustus. He started to preach in the 15th year of Tiberius.”11

This introductory text of Eusebius was contradicted and ignored in the main body of the book. Instead, Jerome preferred the opinion of another Church writer, Tertullian, who wrote that in Olympiad 194.3 (2 BC) “Jesus Christ, the Son of God, was born in the 41st year of Augustus, and suffered in the 15th year of Tiberius.” 12

Jerome’s tables show that Augustus began his reign in Olympiad 184.2 (43 BC). Aside from the Olympiad date introduced, if one subtracts 41 from Augustus’ start date, this will make Tertullian’s birth-date at 2 B.C. which is one year earlier than Eusebius earlier account.

The Chronicon Paschale

A later edition of Jerome’s Chronological Tables was annotated and expanded in the 7th century. It was named the Chronicon Paschale. This work gave further evidence of Christ’s birth date:

Caesar Augustus, also called Octavius, became the second emperor of the Romans, for 56 years and six months. He reigned for 12 years before the death of Cleopatra, and for another 30 years after her death when he conquered Egypt until our Lord Jesus Christ was born in the flesh at Bethlehem in Judaea. After this, he reigned for a further 14 years.13

This table believed that Caesar Augustus began his reign in 42 BC and reigned for 56 years, which would make his end date at 14 AD, which is consistent with most other histories. He reigned for 12 years before the Battle of Actium and the death of Cleopatra. If one subtracts 12 from 42 AD, this will make it 30 BC. The table then asserts that Christ was born 30 years later. This calendar logically arrives that Christ was born at 1 BC/AD (Remember there was no zero back then).

The Census of Quirinius

The Book of Luke narrates that Christ was born during a census taken by Quirinius. The passage reads:

And it came to pass in those days, that there went out a decree from Caesar Augustus that all the world should be taxed. (And this taxing was first made when Cyrenius was governor of Syria.)[Note] Luke 2:1-2 KJV [/note]

The census by Quirinius has caused some major headaches in multiple disciplines. There are no records available today demonstrating that Quirinius was Governor at 1 BC/AD or close. Josephus wrote that Quirinius was a Roman senator who was sent to Syria to clean up a legislative account and conclude on taxings. This happened in the 37th year after the Battle of Actium,14 which would place it somewhere around 6 AD. Some have theorized that he was Governor twice, the first one not being included in any history. 15

Eusebius had no problem with the Quirinius Governership dating problem at all, claiming that Josephus wrote that he was in office during the time of Christ’s birth16, though his argument is not totally convincing.

Some would argue that the ancient third-century apologist Tertullian tried to correct this view by stating that the census was done by Sentius Saturninus, who governed this area 9 to 6 BC.17

Fourth-century historian, Paulus Orosius, didn’t seem to have a problem with the census, believing it to be a natural outcome of one of the most peaceful times in Roman history–a condition for the Messiah’s arrival. Paulus was a contemporary and pupil of St. Augustine, commissioned to make a history of the world from a Christian perspective and wrote a book titled, Historiae Adversum Paganos. In it, he refers to a political person named Gaius and him imposing a census on the land during Christ’s advent. Whether this connects with the census account, I am not sure. This is placed here because it may contain a clue among so few pieces available.

postquam redemptor mundi, Dominus Iesus Christus, uenit in terras et Caesaris censu ciuis Romanus adscriptus est, dum per duodecim, ut dixi, annos clausae belli portae beatissima pacis tranquillitate cohibentur, Gaium nepotem suum Caesar Augustus ad ordinandas Aegypti Syriaeque prouincias misit.18

After the redemptor of the world, the Lord Jesus Christ, came into the land, and a fellow citizen had been reckoned by Caesar’s census, since it was said, 12 years the closed doors of war continued to be held shut in a most glorious tranquility of peace, Augustus Caesar sent his grandson Gaius to continue to keep the provinces of Egypt and Syria in order.19

Paulus held the birth to be 752 years after the founding of Rome (1 BC). Gaius’ coming had to have happened before 4 AD, the year he died from wounds sustained in battle.

The idea that Christ was a Roman citizen is not tenable. Paulus was attempting to make Christ a universal identity in Romanesque terms.

Jerome’s Chronological Table has a scant reference to Quirinius: “Quirinius, sent to Judaea by a resolution of the senate, makes a survey of men and property.” Placing this occurrence at 1 BC20 He cited nothing to support this claim.

A good article that goes into more detail on Quirinius can be found in the Schaff-Herzog Encyclopedia of Religious Knowledge.

Final thoughts

The Regnal system existed as an authoritative calendar even up to the 6th century, having been adjusted and tweaked by the Church Monk, Dionysius Exiguus, whose adaptation first introduced the standard acronym, A.D. There is much more religion, politics, science, mathematics, and astronomy involved before it settled to today’s standard. More on Dionysius’ work can be found Dionysius Exiguus and the AD Calendar System.

It is clear that the Regnal system had serious weaknesses, the biggest ones being that it was too general, the exact reigns of the monarchs were never universally accepted by the ancient authorities, and minor leaders such as Quirinius are hardly known at all. This flaw allows for deviation, and at critical junctures an imprecision of two to four years.

Because of this problem, the ancient chronographers had difficulty dating the time around Christ. Most ancient chronographers cite the Regnal system in historical terms but use another method such as Olympiads, Indictions, Anno Mundi, or others to substantiate their timelines.

To get a firmer date than the regnal, other time calendars used will have to be investigated.


  1. Luke 2:2
  2. Luke 3:1ff
  5. IBID
  6. IBID
  7. IBID
  9. Eusebius, Church History, Book III:V:

    It was in the forty-second year of the reign of Augustus and the twenty-eighth after the subjugation of Egypt and the death of Antony and Cleopatra, with whom the dynasty of the Ptolemies in Egypt came to an end, that our Saviour and Lord Jesus Christ was born in Bethlehem of Judea, according to the prophecies which had been uttered concerning him. His birth took place during the first census, while Cyrenius was governor of Syria.9

  11. St. Jerome ( Hieronymus ): Chronological Tables – for Olympiads 170 to 203 [= 100 B.C. – 36 A.D.] This translation is based on the old edition by A.Schoene. See Olympiad 194.3
  12. See Olympiad 184.3
  13. William Whiston trans, The Works of Josephus. Massachusetts: Hendrickson Publishers, 1982. “Antiquities of the Jews” XVIII:II:1, pg. 377
  15. Eusebius, Church History, Book III:V “3 See Chapter 5,
  16. Tertullian, “Five Books Against Marcion” Book IV:IX, Ante-Nicene Fathers Vol III
  17. IBID Orosii, Book 7, 3:4
  18. My translation

2 thoughts on “The Birth-Year of Christ according to the Regnal System”

  1. During the early Middle Ages, say 5th to 8th century, what dating system was used in western Europe, and, for that matter, in Constantinople & the eastern “Roman” empire? The AD system, as far as I understand, was not broadly disseminated and accepted until after Bede, who died in 735 AD. Were people still using AUC, Ab Urbe Condita, dating from 753 BC? If they used a regnal system, whose reign?
    Maximas gratias tibi ago.

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