When Did the Last Supper Occur?

Matthew, Mark, and Luke clearly state that the Last Supper occurred at the start of Passover, specifically on Passover Eve. John states that it happened the day before Passover Eve. This is just one of the discrepancies between John and the gospels of Matthew, Mark and Luke, commonly referred to as the synoptic gospels, that has confounded scholars over the ages. When the focus of each of the gospels is on the events leading to the crucifixion and following the resurrection, why do the gospels differ on this very important date? Professor Colin Humphreys, a professor of materials science from the University of Cambridge and author of the book “The Mystery of the Last Supper”, thinks the answer lies in which calendar was used. Humphreys believes that the writers of the older synoptic gospels used an old Jewish calendar while the author of the gospel of John used a relatively newer, but more commonly used, lunar calendar to date the event. "In John's Gospel, he is correct in saying the Last Supper was before the Passover meal. But Jesus chose to hold his Last Supper as a Passover meal according to an earlier Jewish calendar," Professor Humphreys explained on the BBC's Today program.

Maundy Thursday, more commonly referred to as Holy Thursday in the United States, is the movable Christian holy day celebrated the Thursday before Easter. Maundy Thursday has traditionally commemorated the date of Last Supper. However, according to Humphreys calculations, the last supper actually occurred on Wednesday, April 1, 33.