When Jesus died, how long was it dark?

Three hours

From the sixth hour there was darkness over all the land unto the ninth hour. Matthew 27:45

And when the sixth hour was come, there was darkness over the whole land until the ninth hour. Mark 15:33

And it was about the sixth hour, and there was a darkness over all the earth until the ninth hour. Luke 23:44

Three days

In that day that he shall suffer death the sun shall be darkened and refuse to give his light unto you; and also the moon and the stars; and there shall be no light upon the face of this land, even from the time that he shall suffer death, for the space of three days. Helaman 14:20

Darkness should cover the face of the whole earth for the space of three days. Helaman 14:27

It came to pass that it did last for the space of three days that there was no light seen. 3 Nephi 8:23