Calculate the actual riser height by dividing the 36 inches by 7 inches. 7 inches is standard for riser height. This will tell you exactly how many treads you will need. Once you divide 36 by seven, you will come up with the answer: 5.143.
Round up to the next whole number to determine the total number of treads. For 3 foot divided by 7 inches, it will equal 5.143, which you round up to six.
Decide whether you want 10-inch, 11-inch or 12-inch tread widths. This will determine exactly how deep each tread will be. The deeper the tread, the less steep the stairs will seem.
Measure the available space for the stairs. The stairs must be a minimum of 36 inches wide.
Outline the length and width for the tread in 1-inch solid wood. Outline each of the six treads.
Cut the treads out of the wood with a handsaw.