How to Measure Stair Rise and Run

Place a long level or a straight edge on the finished floor of the lower level, extending it to the edge of the upper level's finished floor. Measure the vertical distance from the lower finished floor to the point where the level/straight edge meets the upper finished floor. This measurement is the total rise of the staircase.

Divide the total rise (measured in step 1) by a target riser height. Common riser heights range from 7 to 8 inches. For example, if the total rise is 100 inches, dividing by 7.5 inches gives approximately 13.33. Round this number to the nearest whole number to determine the number of risers. In this example, 13 risers would be the target.

Using the total rise and the rounded number of risers from the previous step, divide the total rise by the number of risers to calculate the precise height of each individual riser. For the example of a 100-inch total rise and 13 risers, the actual riser height would be 100 inches / 13 risers = approximately 7.69 inches per riser.

For any staircase, the number of horizontal treads (the surfaces you step on) will always be one less than the number of vertical risers. If you determined you need 13 risers, you will need 12 treads.

This measurement is typically determined by multiplying the number of treads by the desired tread depth. Common tread depths range from 9 to 11 inches. For example, with 12 treads and a desired tread depth of 10 inches, the total run would be 120 inches.

Using the total run and the number of treads, divide the total run by the number of treads to calculate the precise depth of each individual tread. For the example of a 120-inch total run and 12 treads, the actual tread run would be 120 inches / 12 treads = 10 inches per tread.