This has been confusing to some because during that period of history, the Jews and Romans used different methods to calculate time.
The Jews numbered the twelve hours of day from sunrise. They numbered the twelve hours of night from sunset. The Romans counted from midnight and again from noon, as is commonly done today. The Synoptic gospel accounts (Matthew, Mark, Luke) use the Jewish method. John’s gospel account records the hours using the Roman method.
John 19:14 states, “And it was the preparation of the Passover, and about the sixth hour…” This was approximately three hours prior to Christ’s crucifixion, and referred to the general time of sunrise, based on the Roman method.
By today’s standards of time (based on the Roman system), Christ was crucified at about nine o’ clock in the morning. The Jews considered it to be three hours after sunrise (hence, the “third hour” [Mark 15:25]). Darkness spread over the land at about noon (Roman time: twelve hours past midnight; Jewish time: six hours past sunrise [Matt. 27:45; Mark 15:33; Luke 23:44]), lasting until three o’ clock in the afternoon, Roman time (nine hours past sunrise, Jewish time).
We read in Isaiah 28:9-13 that the Bible is written in such a way that every minute detail of any given subject is not presented in any one place. It is like a jigsaw puzzle, each piece fitting together in a certain way in order to fully grasp the big picture.
Once the various pieces from the gospel accounts are put together, it can plainly be seen that they do not contradict each other. Each account complements and supports the others, once the way they were written is understood.