I reproduce his post here in full (because I go back to it often and want to make sure its available), but you should look at it on his site and read some of the interesting discussion/comments that follow if you’re interested in it.
Christians celebrate Christmas and Easter every year, but few know when Jesus was actually born and when he died. With Christmas less than 3 months away, some of you may find the following post helpful. Not that any great doctrine rests on the calculations below, but it sure is nice that we can have reasonable confidence that the dates of Jesus’ birth and death are secure and can be gleaned from a combination of biblical and extrabiblical historical data. I may not be willing to stake my life on the accuracy of the data below, but I am confident enough of these calculations that the license plate of my van reads as follows: 5BC–AD33. So here you go:
Jesus’ birth most likely took place in late November of 5 B.C. (the most authoritative treatment of which I am aware is Paul L. Maier, “The Date of the Nativity and the Chronology of Jesus’ Life,” in Chronos, karios, Christos: Nativity and Chronological Studies Presented to Jack Finegan [ed. J. Vardaman and E. M. Yamauchi; Winona Lake, IN: Eisenbrauns, 1989], 113–30). This, incidentally, would allow enough time for Jesus to be born and for Herod (who died in 4 B.C.) to mount his campaign to have all the boys two years old and under in Bethlehem and vicinity killed (see Matt 2:16, 19).
Jesus’ crucifixion probably occurred on Friday, April 3, A.D. 33. Luke 3:1–3 tells us that John the Baptist, Jesus’ forerunner, began his ministry “in the 15th year of the reign of Tiberius Caesar.” Both Roman historians Tacitus (Annales 4 §4) and Suetonius (Tiberius 73) date the beginning of Tiberius’s reign at A.D. 14 (the precise date is August 19, the day of Emperor Augustus’s death). Hence the 15th year of Tiberius’s reign, counting from August 19, A.D. 14, brings us to A.D. 29 (14 + 15 = 29).
According to Luke 3:23, Jesus was “about 30 years old” when he began his ministry. If Jesus was born in 5 B.C. (as argued above) and began his ministry, as is indicated by all four Gospels, shortly after that of John the Baptist (that is, in the latter part of the year A.D. 29), this would mean that Jesus was about 33 years old when he began his public ministry (see H. W. Hoehner, Chronological Aspects of the Life of Christ [Grand Rapids: Zondervan, 1977], 31–37 and B. Messner, “’In the Fifteenth Year’ Reconsidered: A Study of Luke 3:1,” Stone-Campbell Journal 1 : 201–11).
John’s Gospel records Jesus’ appearance at at least 3 Passovers: (1) in Jerusalem (2:13, 23); (2) in Galilee (6:4); and (3) again in Jerusalem (11:55; 12:1). In addition, it is likely that he attended a fourth Passover not recorded in John but recorded in the Synoptics (Matt 12:1 pars.?). This adds up to a length of about 3 ½ years for Jesus’ ministry. If he began his ministry in late A.D. 29, this brings us to A.D. 33 for the crucifixion. It so happens that because of astronomical calculations A.D. 30 and 33 are the only possible dates for Jesus’ crucifixion as far as the date of Passover in these two years is concerned (for the dating of the four Passovers in question see esp. C. J. Humphreys and W. G. Waddington, “The Jewish Calendar, a Lunar Eclipse, and the Date of Christ’s Crucifixion,” Tyndale Bulletin 43 : 331–51, esp. 335).
Finally, John 2:20 says that the temple was completed 46 years ago (see for this translation A. J. Köstenberger, John [BECNT; Grand Rapids: Baker, 2004], 109–10). According to Josephus, the renovation of the temple building proper started in 20/19 B.C. (Antiquities 15.11.1 §380), with completion 18 months later in 18/17 B.C. (Antiquities 15.11.6 §421). Again, counting from 18/17 B.C., adding 46 years brings us to A.D. 29 (there was no year zero)—a great way to check our math above!
For Further Study: See the chart in A. J. Köstenberger, John (BECNT; Grand Rapids: Baker, 2004), 11–13, and commentary at 1:19 and 2:20, and the previous post on Johannine chronology here. See also H. W. Hoehner, “Chronology,” in Dictionary of Jesus and the Gospels (ed. J. B. Green, S. McKnight, and I. H. Marshall; Downers Grove, IL: InterVarsity, 1992), 118–22.