Stair Carpet Calculator

About the Stair Carpet Calculator

Carpeting stairs requires a different measurement approach than carpeting a flat room. Each step consists of a horizontal tread, a vertical riser, and a nosing (the overhang at the front of the tread). The carpet must wrap over each of these surfaces continuously, which means the total carpet length is not simply the vertical height of the staircase.

This stair carpet calculator determines the total linear feet of carpet needed by measuring each step as a combination of tread depth, riser height, and nosing overhang. It accounts for all steps and the width of the staircase to calculate the total carpet yardage. The result works for both wall-to-wall stair carpet and stair runners.

Stair carpet takes significant abuse from foot traffic, so it's important to choose a durable, low-pile carpet and have enough material for a tight, wrinkle-free installation.

When This Page Helps

Stair carpet requires precise length calculations because carpet wraps over each step rather than laying flat. Under-measuring by even a foot can leave the bottom step uncovered. This calculator ensures you order the exact amount.

How to Use the Inputs

1. Count the number of steps (treads) on the staircase.
2. Measure the tread depth (front to back, including nosing) in inches.
3. Measure the riser height (bottom of one tread to bottom of the next) in inches.
4. Measure the stair width in inches.
5. Add an allowance for the top and bottom landing if applicable.
6. Review the total linear feet and square yardage.

Example Calculation

Tips & Best Practices

• Use a low, dense pile carpet for stairs — it wears better and is safer underfoot.
• Waterfall installation wraps carpet over the nosing and down the riser.
• Hollywood installation tucks carpet under the nosing for a tailored look.
• Add 2–3 feet to the total length for tucking at top and bottom landings.
• Stair runners should be 2–4 inches narrower than the stair width on each side.
• Use heavy-duty padding rated for stairs (not regular room padding).

Measuring Your Staircase

Measure the tread depth from the back of the step to the front edge (nosing). Measure the riser height from the top of one tread to the top of the next. Add 1–1.5 inches per step for the carpet to tuck under the nosing. Count all steps including the landing step.

Installation Styles

Waterfall installation drapes the carpet straight over the nosing and down the riser like a waterfall. It's easier and uses less carpet. Hollywood or cap installation wraps the carpet tightly around the nosing, following the step profile. It looks more tailored but uses slightly more material.

Stair Runner Considerations

Runners leave 2–4 inches of bare stair on each side. The exposed wood can be stained and finished for a decorative look. Runners require rods or clips at each step to hold them in place. Some runners use pad underneath while others are bound and backed.

Cost Breakdown

Stair carpeting typically costs $10–$25 per step installed, including carpet and pad. A 13-step staircase runs $130–$325. Premium runners or full-width carpet on a curved staircase can cost $500+.

Frequently Asked Questions

• How much carpet do I need for 13 stairs?

  A typical 13-step staircase with 10” treads and 7.5” risers needs approximately 22–25 linear feet of carpet plus landing allowance. The exact amount depends on tread depth, riser height, nosing, and installation style.

• What is the best carpet for stairs?

  Low-pile or loop-pile nylon carpet is the most durable for stairs. Avoid thick plush or shag — it wrinkles on stair edges and shows wear quickly. Patterned carpet hides dirt and traffic paths.

• What width carpet do I need for stairs?

  Wall-to-wall stair carpet needs the full stair width (usually 36”). Stair runners are typically 27” or 30” wide, centered on the stair with bare wood exposed on each side.

• How are stair carpet and room carpet different?

  Stair carpet must bend over each step edge without buckling. It requires denser, lower-pile fabric and heavier padding specifically rated for stairs. Standard room carpet and padding may not hold up on stairs.

• Can I install stair carpet myself?

  It's one of the more challenging carpet DIY projects. You need a knee kicker, stair tool, and strong hands. Many homeowners hire a professional for stairs even if they DIY the rest of the house.

• How do I measure for a stair runner?

  Measure one step (tread + riser + nosing tuck) and multiply by the number of steps. Add 2–3 feet for top and bottom landings. Multiply by the runner width and convert to square yards.