How To Calculate Stairs For Even and Comfortable Steps

1. Measure the total height between each floor and the next by feet (between 1st and 2nd then 2nd and 3rd and so on)

2. Decide on wood type to use for framing the stair treads.

3. To get an approximate number of steps, divide the total height computed in (1) by 7.  The total will be the number of risers you will need.

4. Round the total up to a whole number and divide the height measured from (1) to this total.  This will get you the actual height between one riser to another.

5. Subtract the number derived in (4) from 18 inches, the standard total of rise and tread for individual stairs.   The resulting number will be the average tread.

6. To get the total run of the stairwell, multiply the tread measurement from (5) to the rounded number of risers in (4.)

7. To get the length of the stairwell, get the square root of the total height (1) squared plus the total run (6) squared. Here’s the notation: root of [(1)*(1) + (6)*(6)]

8. Add 10% to the figure arrived at in (7) and round up to an even number.  This is the total length of material (in feet) you will need for the stair jacks.

9. Multiply the rounded number of risers (3) by the width of your stairs and the height between each riser (4). Do the same for the number of treads (3) multiplying by the width and the average unit tread (5.)  Add both results to get the total amount of material you will need.