How to Calculate the Amount of Carpet Runner Needed for Your Stairs


Whether you’re a DIYer installing a carpet runner on stairs or you’re a conscientious planner working within a budget, calculating the amount of carpet runner you’ll need is a quick, 20 minute exercise.

(*Special Note: We always recommend using a licensed, insured installer when working on stairs.)

Step 1: Decide On A Width


Standard width for a carpet runner on stairs ultimately depends on the width of your stairs, but a good rule of thumb is that you want 4-5 inches of exposed stair on each side of the carpet runner.

If your stairs are 36 inches wide, then you want a runner 27 inches wide. If you have wider stairs, say 48 or 60 inches wide, you could easily extend the exposed area to 6-8 inches on either side. Ultimately, your goal is to avoid having too narrow a strip of carpet running down your stairs because it will increase the likelihood of slipping rather than reduce it.

If your stair treads underneath are plain wood — without the bullnosing typical of finished treads — then you will probably want a full width carpet runner covering the entire tread and riser.

Step 2: Calculate the Length

To approximate the amount of carpet runner by the foot that you’ll need to order, you want to measure the amount needed for each stair and then multiply by the number of stairs that you have.

Add at least 24 inches to the entire order to account for cutting and fitting. Stair runners are not typically installed in one piece — they are cut into individual stair pieces and then fitted together so they appear to be one solid piece. This reduces bunching and creates nice, clean lines.

Your stair has 3 parts that need to be measured: the tread, the front edge, and the riser. The length of the tread is measured from the bottom of the previous riser to the front edge. The front edge is often rounded and curves underneath until it meets the riser. Use a piece of string or cord to determine the length around the front edge and then measure your string. The riser length is measured from top to bottom. Add the 3 lengths together and then multiply by the number of stairs.

If you’ve measured in inches, make sure to convert to feet by dividing the total length by 12. Also, if you carry your carpet runner through any landings, don’t forget to measure the length of each landing.

Step 3: Order Your Carpet Runner

Typically, carpet runners come in standard widths, anything from 3 feet to 12 feet, but you can have them cut to fit exact widths down to the inch of what you need. Once the width is determined, you purchase carpet runners by the foot and have it cut to the length you calculated, plus 24 inches to account for cuts.

Place your order with a reputable local carpet supplier or you can place your order online and have your carpet runner delivered to your home.

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