The Christian Bible does not specify the actual dimensions of Jesus' cross. The scriptures do give clues that allow an educated guess at the size and weight of the cross.
In Mark 15:36, the scripture reads that Jesus was offered a sponge with vinegar stuck to a hyssop reed. The average height of a male in that time period was approximately 5 feet, and the reed of a hyssop averages 1 to 2 feet long. These figures indicate that the cross was approximately 7 to 9 feet tall. The patibulum that Jesus' arms were outstretched and nailed to was likely 5 to 6 feet long. The entire cross is estimated to have weighed well over 300 pounds.