Stair Carpet Calculator

Frequently Asked Questions

How many square yards of carpet for 14 stairs?

With 36 in width, 10 in tread, 7.5 in riser, and 15% waste: (10+7.5) x 36/144 x 14 x 1.15 = 70.4 sq ft / 9 = 7.8, so 8 square yards.

What waste factor should I use for stair carpet?

Use 15% as a minimum. If you have a patterned carpet that requires matching at each stair, use 20-25%.

What is the standard riser and tread size for residential stairs?

IRC requires risers between 4 and 7.75 inches and treads at least 10 inches deep. Most homes use 7-7.5 in risers and 10-11 in treads.

Can I use regular room carpet on stairs?

Any carpet can technically go on stairs, but loop piles (Berber) can snag and are not recommended. Cut-pile and textured cut-pile are best for stair durability and safety.

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How This Calculator Works

Each stair requires carpet to cover both the tread (horizontal surface you step on) and the riser (vertical face). The area per stair is (tread + riser) x width in square inches, converted to square feet. Adding all stairs gives total area; the waste factor handles cutting and pattern matching.

Formula: area_per_stair = (tread_in + riser_in) x width_in / 144. Carpet is sold by the square yard (9 sq ft), so the calculator also shows yards needed.

Standard Stair Dimensions

IRC code requires risers between 4 and 7.75 inches and treads at least 10 inches deep (nosing included). Most residential stairs use:

Riser: 7-7.5 inches

Tread: 10-11 inches

Width: 36 inches (minimum code for residential)

Measure your actual stairs rather than assuming standard dimensions. Older homes often have non-standard measurements.

Carpet Installation Methods for Stairs

Three main methods for carpeting stairs:

Waterfall: carpet falls over the nose of the tread and down the riser without turning. Fastest to install, requires less carpet since there is no extra material turned under the nose.

Cap and band: carpet wraps over the nose and is tucked under the tread. More professional look, requires slightly more carpet.

Runner: a narrow strip of carpet runs down the center of the staircase, leaving wood exposed on each side. Uses less carpet; measure runner width carefully.

FAQ

How much carpet for 14 stairs?

With a 36 in wide stair, 10 in tread, 7.5 in riser, and 15% waste: (10+7.5) x 36 / 144 = 4.375 sq ft per stair. 14 stairs x 4.375 = 61.25 sq ft x 1.15 waste = 70.4 sq ft / 9 = 7.8, round up to 8 square yards.

Is carpet sold by the square yard or square foot?

Carpet is priced per square yard but you can buy it in any quantity. Most rolls are 12 ft wide. A square yard = 9 sq ft. Always add 10-15% for waste and pattern matching on stairs.

Do I need special carpet padding for stairs?

Yes. Use a dense pad rated at least 8 lb density for stairs. Soft, thick pads compress under foot traffic on the nose and can become a trip hazard. Waffle pads are not suitable for stairs.

How do I measure for stair runner carpet?

Measure the runner width you want (typically 27-36 in), not the full stair width. Multiply runner width by the total length of one full stair measurement (tread + riser) times the number of stairs, then add 15-20% waste.

Stair Carpet Calculator

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