OK, tore out the old stairs. I bought 6 step risers and they were too long. I exchanged them for 5 step risers. They were too short. In looking at the original stairs, the saw cuts tell me they were built-on-site. OK, I have three treated 2X10X10s. I'm needing the formula to measure and cut to get started. The measurement from the bottom of the deck board to the ground is 45 inches. The floor joist, I guess that is what it is, is 2X8. BTW, the old stair risers are in pieces- got that way to get it off the deck. Any help or suggestions or Internet sites are most welcome.