How to Calculate Stair Runner Rug Size

Measure the depth of each tread on your stairs with the tape measure. Sometimes treads vary in depth, making it important that you measure the depth of each stair so you don’t run short when installing the runner rug. Record the measurements for each stair’s tread on a piece of paper.

Use a diagonal measuring technique to measure the height of the riser by placing the measuring tape on the lip of one tread and stretching it to the point where the bottom riser and the next tread come together. Write this measurement down on the paper.

Multiply the total number of stairs by the riser measurement.

Add all of the tread measurements together, and add this to the riser measurement total.

Calculate the length of rug you want to use on the landing at the top and bottom of the stairs and add it to your riser and tread total. Allow more than eight inches of runner on the top landing to avoid catching your foot and tripping. Some people do not extend the rug at the bottom of the stairs; instead tacking it in place at the bottom of the stairs, where the riser meets the floor.

Divide the final measurement by 12 to determine the length of the rug you need in feet.

Measure the width of the stairs, keeping in mind that most runner rugs measure about 2.5 feet in width. Rugs are available for widths of two or three feet, but the choices narrow considerably due to the less popular size.