How Much Carpet for Stairs Do I Need?
Quick answer: steps × tread+riser area, plus landings. A standard 36-inch step is about 3.6 sq ft (tread 12 in + riser 8 in = 20 in × 36 in). 13 steps need about 47 sq ft of carpet, plus a landing — a runner uses roughly half.
- One step = tread + riser
- Full coverage vs runner
- Landings add up
- Stair widths and waste
- Worked example: 13 stairs
- FAQ
One step = tread + riser
Measure one tread (the horizontal part, about 11–12 inches) plus one riser (the vertical part, about 7–8 inches) as a single unit — typically about 20 inches. Multiply by the stair width (usually 36 inches) for the area per step: 20 in × 36 in ≈ 3.6 sq ft.
Full coverage vs runner
Full coverage carpets every step and both edges. A runner leaves the edges exposed — typically 27–36 inches wide on a standard 36-inch stair — and uses about 50–75% of the carpet. Runners are cheaper and highlight the treads; full coverage is quieter and softer.
Landings add up
Landings are measured as rectangles and added to the step total. A typical 3×5 landing adds 15 sq ft. Top landings and halfway landings both count — forgetting them is the most common underestimate in stair carpet.
Stair widths and waste
Carpet comes on 12-foot rolls, so the roll width rarely matches the stair width — offcuts happen. Add 10% for fitting around nosing, curves and seams at landings. Odd-sized or curved stairs may need more.
Worked example: 13 stairs with a landing
- One step = 20 in × 36 in ≈ 3.6 sq ft
- 13 steps × 3.6 = 46.8 sq ft
- Landing 3×5 = 15 sq ft
- Total + 10% waste ≈ 68 sq ft
- Runner version → about 30–40 sq ft
FAQ
Multiply the number of steps by the tread-plus-riser size, then add the landing. A standard 36-inch step is about 3.6 sq ft, so 13 steps need about 47 sq ft, plus a landing.
About 47 sq ft, plus a landing. 13 steps × 3.6 sq ft = 46.8 sq ft. Add a 3×5 landing and waste, and you're near 65 sq ft. A runner uses roughly half.
A runner is typically 27–36 inches wide, so it uses about 50–75% of full-coverage carpet. For 13 steps you'd need roughly 25–35 sq ft of runner carpet.
Measure one tread plus one riser as one unit (about 20 inches), multiply by the stair width, then by the number of steps. Add landings separately.
Yes — add 10% for fitting around nosing, curves, and seams at landings. Carpet comes on 12-foot rolls, so odd stair widths create offcuts.