Work out how many square yards of carpet your staircase needs. Free stair carpet calculator handles landings, hallway runs, pattern repeats, and cost.
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Carpet on stairs isn’t a simple area calculation. Each step has a tread you walk on, a riser behind it, and a nosing that wraps over the edge. Stack fourteen of those and you’ve got a developed length much longer than the horizontal run a tape measure gives you. This stair carpet calculator handles that math. Enter tread depth, riser height, and nosing allowance, and the tool builds a developed length, multiplies by stair width, then adds any landing or hallway you’re covering. It returns square yards to order, linear length along the roll, underlay and gripper rod quantities, and a cost estimate. Pattern repeats get their own matching allowance, and the tool checks whether your stair width fits inside a standard roll. Imperial and metric both work, and everything runs in your browser.
Choose your unit system. Imperial uses inches, feet, and square yards. Metric uses millimeters, meters, and square meters.
Pick a stair configuration preset, or set the number of steps, tread depth, riser height, and stair width by hand.
Set the nosing allowance. 1.5 inches is typical for a wrapped nosing. Bump it higher if your carpet is thick or you’re folding around a bullnose.
Add a landing if the stairs turn. Enter the landing length and width.
Add a hallway if you’re carpeting the run-up. Enter its length and width.
Pick your carpet roll width. 12 feet is standard. 15 feet works for wide landings.
Choose the pattern type and repeat. Plain adds no allowance. A patterned carpet adds one repeat per junction to keep the pattern lined up.
Set the waste factor. 10% is standard for plain carpet.
Toggle underlay, gripper rod, and binding. Enter binding length only if you’re wrapping exposed edges.
Add unit costs and read the result. The output panel shows total carpet to order, linear feet along the roll, and total cost.
The core calculation is developed length. Each step contributes one tread depth, one riser height, and one nosing allowance. Multiply that per-step figure by the number of steps and you have the total length of carpet that runs up the staircase before any width is applied.
Formula: Developed Length per Step = Tread Depth + Riser Height + Nosing Allowance
Formula: Total Developed Length = Developed Length per Step × Number of Steps
Formula: Stair Surface Area = Total Developed Length × Stair Width
Formula: Total Installed Area = Stair Area + Landing Area + Hallway Area
Formula: Linear Length Along Roll = (Total Installed Area ÷ Roll Width) + Pattern Allowance
Formula: Carpet to Order = Linear Length Along Roll × Roll Width × (1 + Waste % ÷ 100)
Formula: Square Yards to Order = Carpet to Order Area ÷ 9
A few details matter here. First, developed length uses tread plus riser, not just tread. A 14-step flight with an 11-inch tread and a 7.25-inch riser has a per-step figure of 18.25 inches before the nosing. That’s the number most hand calculations miss.
Second, the linear length along the roll assumes the carpet runs up the stairs in one continuous strip. If your stair width exceeds the roll width, you’ll need a seam, and the tool flags it in the result panel. A 12-foot roll covers almost any residential stair, so the warning typically only fires on 15-foot rolls with very wide landings.
Third, pattern repeats get added once per junction, not once per step. Junctions are points where the carpet changes direction or meets a new section: stair-to-landing, landing-to-hallway, and so on. The tool counts them from your toggles and adds one repeat length for each.
Fourth, waste sits on top of everything. The default 10% covers cuts and seams. A patterned carpet with a large repeat usually needs 15%.
Underlay area equals installed area. Gripper rod length is calculated from the perimeter of each section: two side runs along the stairs plus the landing and hallway perimeters.
A 14-step straight flight with a small landing at the top and a hallway running to a bedroom. Numbers below.
Stair inputs: 14 steps, tread 11 in, riser 7.25 in, nosing 1.25 in, width 34 in.
Landing: 5.5 ft × 3.5 ft.
Hallway: 10 ft × 3 ft.
Roll width: 12 ft. Pattern: plain. Waste: 10%.
Step 1 – Developed length per step. 11 + 7.25 + 1.25 = 19.5 in.
Step 2 – Total developed length. 19.5 × 14 = 273 in, or 22.75 ft.
Step 3 – Stair area. 22.75 ft × 2.833 ft (34 in) = 64.46 ft².
Step 4 – Landing and hallway. 19.25 + 30 = 49.25 ft².
Step 5 – Total installed area. 64.46 + 49.25 = 113.71 ft².
Step 6 – Linear length along roll. 113.71 ÷ 12 = 9.48 ft.
Step 7 – Apply waste. 9.48 × 1.10 = 10.43 ft.
Step 8 – Carpet to order. 10.43 × 12 = 125.16 ft². In square yards: 13.91 yd².
Step 9 – Underlay. 113.71 ft², or 12.63 yd².
Step 10 – Gripper rod. Stairs: 2 × 22.75 = 45.5 ft. Landing: 2 × 9 = 18 ft. Hallway: 2 × 13 = 26 ft. Total 89.5 ft.
Interpretation: Order 14 square yards of carpet. Underlay covers 13 square yards. Gripper rod covers 90 feet. If you were pricing this at $24/yd² for carpet, $7/yd² for underlay, and $1.50/ft for gripper, materials run about $556 before labor.
Developed length accounts for the riser and nosing, which most hand calculations skip.
The roll-width check warns you before you order a roll that’s too narrow for the stairs.
Pattern-repeat allowance gets added per junction, so patterned carpet isn’t under-ordered.
Underlay, gripper rod, and binding are calculated from the same inputs, so the materials list stays consistent.
You can toggle landing and hallway sections on and off to price a stairs-only job or a full floor.
Costs run in the same panel as quantities, which makes comparison shopping simple.
Imperial and metric inputs both work, and densities convert when you switch.
Nothing gets uploaded. The whole calculation runs locally.
Measure one tread, one riser, and the stair width. Add tread plus riser plus a nosing allowance, then multiply by the number of steps. Multiply that total by the width. A 14-step flight at 19.5 inches per step and 34 inches wide needs about 64 square feet of carpet.
Roughly 7 square yards for a typical 13-step flight with a 10-inch tread and 36-inch width. Add 10% waste and you’re at 8 square yards. Landing and hallway areas add separately.
Yes, for almost every residential install. Underlay cushions each step, cuts noise, and helps the carpet keep its shape. Only glue-down installs skip it. The calculator includes underlay at the total installed area.
12 feet is standard and covers nearly every residential staircase. 15-foot rolls are used for wide rooms. If your stair width exceeds the roll width, the tool flags it and you’ll need a seam.
10% for plain carpet. 15% for a pattern with a repeat over 12 inches. 20% if the stairs turn or you have multiple landings. Waste covers offcuts and pattern alignment.
Partially. Enter your runner width as the stair width, and the calculator returns developed length and area. Runner installs leave the wood exposed on both sides, so you skip gripper rod on the visible edges. The tool’s gripper output assumes full-width carpet.
Material costs $12 to $45 per square yard. Underlay adds $4 to $10 per square yard. Gripper is $1 to $2.50 per foot. Labor for a typical 14-step flight runs $150 to $400. A full stair-plus-landing job lands between $700 and $1,500 depending on carpet grade.
The total length of carpet you need to cover a step, measured along the surface. It equals tread depth plus riser height plus nosing allowance. For a step with an 11-inch tread and a 7.25-inch riser, developed length is 18.25 inches before you add the nosing.
Usually yes, because the landing sits between flights and the carpet has to run continuously over it. If the landing stays bare, turn the landing toggle off and the tool drops it from the total.
It’s one of the harder DIY carpet jobs. Stairs need tight tackless strip placement, precise stretch, and a knee kicker or power stretcher. Most homeowners hire a fitter for stairs even when they do the rest of the floor themselves. The calculator gives you the material takeoff either way.
Yes, when gripper rod is toggled on. It computes two side runs along the developed length of the stairs, plus the perimeter of any landing and hallway you’ve added.
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