This page was last updated on 26 July 2016.

Luke 3:1 Now in the fifteenth year of the reign of Tiberius Caesar, Pontius Pilate being governor of Judaea, and Herod being tetrarch of Galilee, and his brother Philip tetrarch of Ituraea and of the region of Trachonitis, and Lysanias the tetrarch of Abilene,

There are several ways dating the reign of ruler. As which many things there is some debate over which method should be used. This page will simply list all those methods.

Tiberius Caesar ruled from 18 September 14 AD – 16 March 37 AD - link
That’s one dating method. Simply use the exact dates for Tiberius reign.

Tiberius became sole ruler when his father Augustus died but Roman historians seem to round to the next year. Meaning they counted as if Augustus reigned until midnight 31 December 14 AD. Tiberius reign started 1 January 15 AD.
15 AD was the first year Tiberius was counted as being ruler.

The Jews had 2 similar methods. The Jewish religious year started in spring.

Exod 12:2 This month shall be to you the beginning of months: it shall be the first month of the year to you.

The Jews had a civil year that started in fall.

Using spring counting Tiberius’ first year of reign started spring 15 AD.

Using fall counting Tiberius’ first year of reign started fall ?? AD.

An explanation of the question marks. 18 September is very close to the boundary of summer and fall. On our calendar it’s clear. Summer ends 21 September.

On the Jewish calendar start of fall is little variable. The Feast of Tabernacles must fall after the 22/23 September equinox. How much varies a bit every year. That’s just one of the side-effects of syncing a lunar calendar to a solar year.

There also is the method of counting the reign of Tiberius from the point he was co-rex. During the last 2 years of his life, Augustus ruled together with Tiberius. That means some count the first year of Tiberius 2 years earlier. I’ve already listed 4 methods of dating and by using the co-rex method that number would double to 8 possible dates. And because Augustus death is on the border of summer and fall we get even more possibilities.

So the dating methods are:

• Use exact dates.
• Co-Rex method.
• Rounded to the next 1 January - Roman method.
• Co-Rex method.
• Rounded to the next spring - Jewish method #1.
• Co-Rex method.
• Rounded to the next fall - Jewish method #2.
• Co-Rex method.

Unfortunately there is more room for confusion…..
Augustus died  19 August 14 AD.
Nearly one month later the Roman Senate appointed Tiberius as emperor.

Tiberius rule starts 18 September 14 AD.

That’s has zero impact on how the Romans counted because both dates are well before 1 January. But for the Jewish civil year it could just make the difference.

So the dating methods are:

• Use exact dates.
• Counting from the death of the previous ruler.
• Co-Rex method.
• Counting from the start of the rule of the new ruler.
• Co-Rex method.
• Rounded to the next 1 January - Roman method.
• Counting from the death of the previous ruler.
• Co-Rex method.
• Counting from the start of the rule of the new ruler.
• Co-Rex method.
• Rounded to the next spring - Jewish method #1.
• Counting from the death of the previous ruler.
• Co-Rex method.
• Counting from the start of the rule of the new ruler.
• Co-Rex method.
• Rounded to the next fall - Jewish method #2.
• Counting from the death of the previous ruler.
• Co-Rex method.
• Counting from the start of the rule of the new ruler.
• Co-Rex method.

Unfortunately the above list shows that no exact date can be picked without room for debate. Fortunately there is a lot of overlap so the list is shorter as it looks.
In the case of Tiberius Roman historians don’t seem to use the co-rex method. Because 1 January (Roman method) is nowhere near  18 September the Roman dating is undisputed. That at least allows us to remove the co-rex methods from the Roman part of the list.

Writings of Roman historians show the first year of a ruler started 1 January following the date the Roman Senate appointed the ruler. So the date of death of the previous ruler isn’t relevant; so can be removed from the list.

The exact dates method wasn’t used by either Jew or Roman so can be removed from the list too.

So the dating methods are:

• Rounded to the next 1 January - Roman method.
• 1 January following the date the Roman Senate appointed the new ruler.
• Rounded to the next spring - Jewish method #1.
• Counting from the death of the previous ruler.
• Co-Rex method.
• Counting from the start of the rule of the new ruler.
• Co-Rex method.
• Rounded to the next fall - Jewish method #2.
• Counting from the death of the previous ruler.
• Co-Rex method.
• Counting from the start of the rule of the new ruler.
• Co-Rex method.

I’m aware some of the methods in the above list are (far) more disputed than others. I just wanted to list all variations I’m aware of and remove the variations that are (almost) certainly wrong.