How to Calculate a Stair Runner

Measure one stair riser (the vertical rise of one stair) by placing the zero end of the measuring tape at the bottom of the riser and measuring the distance to the top of the riser. If there is a lip on the tread part of the stair, do not include the lip measurement in the riser height. Instead measure from the bottom of the riser to the bottom of the lip. Record this measurement.

Number your paper according to the number of stairs you have. If you have 25 stairs, number 1 through 25 on your paper.

Measure the depth of each stair tread and record the measurement. If your staircase has a lip or ledge on each stair, include in this measurement by placing the zero end of your measuring tape against the back of the tread and measuring around the lip to the place where the lip meets the riser. Because it is not uncommon for staircases to have treads of varying depth, you must measure each tread individually.

Multiply the riser measurement by the number of stairs. Then add all of the tread depth measurements together, and add that total to the riser total.

Decide how far you would like the runner to continue on the top and bottom landings, and then add that number to your total to determine the final length needed for a stair runner.

The standard width measurement for stair runners is 2 feet, 6 inches, but it is possible to find runners in widths from 2 feet to 3 feet. As the length of your runner increases, the available widths will likely widen. Measure the width of your stair treads, and then estimate the width of your ideal runner before shopping. Runners with widths greater than 3 feet may have to be custom made.