Determine the total rise for your stairs using a level and a tape measure. Measure the distance from the top of the deck surface to the top of the stair landing. Input the total rise number into the decks.com stair calculator to determine the number of stairs, each stair rise and run for laying out your stair stringers. Example shows outside drop mounted stairs.
Using the information from the calculator mark your rise and run on the framing square. Example shows drawing the top step run at 10" and rise at 6-3/8".
After laying out your rise and run measurements on your 2x12 stair stringer remove 1" from the back of the top run if you plan on installing a 1" thick riser board.
After laying out each rise and run remove the thickness of the tread for the bottom step from the bottom of the rise.
Example using 5/4x6 decking which is 1" thick. Stair rise is 6-3/8", bottom stair stringer rise is 5-3/8". The cut line is in red.
Notice that the stair stinger top step has a 9" run and the next step has a 10" run. The back tread for the top step had to be ripped down to fit the opening.
The bottom step has a 5-3/8" rise. The next step has a 6-3/8" rise. Notice that the stair stringers land on the concrete landing with a 12" bearing.