Stair Carpet Calculator

Estimate carpet for a staircase

This stair carpet calculator estimates the carpet area needed for a straight or repeated staircase. Enter the number of steps, tread depth, riser height, stair width, flights, and landings. Add an allowance for fitting waste and the calculator shows the estimated carpet area in square feet, square yards, and square metres. An optional price per square yard gives a basic material cost estimate.

Unlike a flat room, stairs use carpet across two surfaces on every step: the horizontal tread and the vertical riser. A useful first estimate adds tread depth and riser height for each step, then multiplies by the number of steps and the width of the staircase. Include a landing when it will be carpeted as part of the same job.

Use the result to prepare for a supplier visit, compare a quote, or check how much carpet a stair runner may use. Carpet direction, pattern repeat, nosings, returns, seams, and the installer's wrapping method all affect the final cut. Confirm measurements and the carpet layout with the retailer or installer before placing an order.

How to use the stair carpet estimator

Choose feet or metres, then measure one typical step. Tread depth is the flat part where a foot lands, measured from the front edge to the riser. Riser height is the vertical face between two treads. Stair width is measured from one finished edge to the other. If the stairs are carpeted wall to wall, measure the usable width that the carpet must cover.

Enter the number of steps in one flight and how many matching flights use the same dimensions. If your stairs have different widths or step sizes, calculate each group separately and add the results. Enter the total landing count and the depth of a typical landing. The calculator assumes landings use the same width as the stairs. For a wider or irregular landing, measure that area separately and add it to the order estimate.

Set the waste percentage to allow for trimming and fitting. If you know the carpet price per square yard, add it to estimate material cost. The result also includes a tread-only padding estimate, since some installers place pad on the treads but not the risers. Select the full stair surface option if your planned padding covers both treads and risers.

Stair carpet calculation formula

The main estimate treats the carpet as one continuous strip that follows each tread and riser. It adds the horizontal tread depth to the vertical riser height, then multiplies that step length by the number of steps. Carpeted landings are added as flat sections. Finally, the total run length is multiplied by the stair width to find area.

• Carpet length per step = tread depth + riser height + optional fitting allowance
• Step run length = carpet length per step × steps per flight × number of flights
• Landing run length = landing depth × landing count
• Gross carpet area = stair width × (step run length + landing run length)
• Order area = gross carpet area × (1 + waste percentage ÷ 100)
• Square yards = square feet ÷ 9
• Tread-only pad area = stair width × tread depth × total step count

Worked example: carpet for 12 steps

Suppose a staircase has 12 steps, each with a 10 inch tread and a 7.5 inch riser. The stairs are 36 inches wide, there is no landing in this example, and you plan to use 10 percent extra for fitting. First, add the tread and riser: 10 + 7.5 = 17.5 inches of carpet length per step. Multiply by 12 steps to get 210 inches, or 17.5 feet, of carpet run.

Multiply that run by the 3 foot stair width: 17.5 × 3 = 52.5 square feet. Add 10 percent waste: 52.5 × 1.10 = 57.75 square feet. Divide by 9 to convert to square yards, giving about 6.42 square yards to plan for. A supplier may sell carpet in linear lengths from a wider roll, so the actual cut can be different from the area equivalent.

If the same stairs have a 3 foot deep landing, add its area: 3 × 3 = 9 square feet. The estimated total before waste becomes 61.5 square feet, or 67.65 square feet with the same 10 percent allowance. This example assumes the landing width matches the stairs and the step dimensions repeat evenly.

Measuring treads, risers, and stair width

Measure the tread from the front edge to the back where it meets the riser. If the stair has a rounded nosing, measure the portion that the carpet must cover around it. Measure the riser from the top of one tread to the underside or front edge of the next tread, depending on how the carpet is installed. Keep the same measuring method for every step.

Measure each step rather than relying only on a building plan. Older staircases can have small differences in depth or height. If the dimensions vary, use the largest safe measurement for a conservative estimate or calculate the sections separately. Check the top and bottom steps too; they may have different edges or transitions.

Measure stair width between the points where carpet will stop. A wall-to-wall installation, a stair runner, and a carpet runner with exposed wood on both sides use different widths. Include any side wrapping or tucked edges in the width you enter. Do not measure only the visible flat part if the carpet will wrap around the stair nose.

Flights, turns, and landings

A flight is a continuous run of steps between landings or floors. Use the flight count when multiple runs have the same step dimensions and width. For example, two matching flights with eight steps each can be entered as eight steps and two flights. If the flights differ, calculate each one as a separate estimate so the result reflects its actual dimensions.

A landing is the flat platform between flights or at a floor level. Measure its depth in the direction the carpet continues, and enter its count. This calculator treats each landing as a rectangle the same width as the stair. If a landing is wider, L-shaped, or includes a hallway, estimate its extra area separately with a floor area calculator and add the result to your carpet order.

Winder stairs, curved stairs, spiral staircases, and pie-shaped treads need careful templates. A simple tread-plus-riser formula cannot account for tapered geometry or the way carpet turns at a corner. Use the estimate as a starting point and have the installer measure those stairs directly before cutting carpet.

Carpet area, square feet, and square yards

Carpet area may be quoted in square feet or square yards. One square yard equals 9 square feet. If your result is in square feet, divide by 9 to get square yards. The calculator displays both units so you can compare the estimate with a supplier's product pricing and quote.

An area conversion is not always the same as the amount cut from a carpet roll. Broadloom carpet is commonly sold in a fixed roll width, and the installer may need a length that fits the stair run, pattern direction, and seam plan. A narrow stair runner can also be cut from a wider roll, leaving unusable offcuts. Ask the supplier how its price and minimum order length are measured.

Use the carpet's stated width and pattern repeat when discussing a purchase. The calculator estimates coverage area; it does not draw a cutting layout or guarantee that every offcut can be reused on another staircase.

Carpet waste and pattern allowance

Waste allowance covers trimming, fitting, damaged edges, and pieces that cannot be reused. A straight staircase with matching steps may have a simple layout, while multiple flights, wide landings, turns, and unusual nosings can create extra cuts. Patterned carpet may need more material to keep the design aligned from one tread to the next.

There is no single waste percentage that suits every stair. Choose an allowance with the carpet installer or retailer, especially for patterned carpet or a stair runner. If a quote already includes extra material, do not add the same allowance twice. The calculator rounds no package quantities because carpet is often ordered by area or cut length rather than cartons.

Carpet direction and pile can change how color looks under stair lighting. Matching a landing and several flights may require the pieces to run in a particular direction. These layout choices can matter more than the simple area total, so treat waste as a planning setting rather than a guaranteed cutting plan.

Carpet padding for stairs

Padding can improve the feel of carpet and help protect the stair covering, but its placement depends on the carpet and installation method. Some stair installations use pad on the tread and wrap the carpet over the riser without padding the vertical face. Other systems may cover more of the stair surface. Ask the installer which method and pad type are suitable for your carpet.

This calculator provides both tread-only padding area and a full-surface area based on the selection you make. The tread-only result multiplies tread depth, stair width, and total step count. It does not subtract nosings, allow for pad seams, or estimate fasteners. Add a waste allowance for pad cuts if your installer recommends it.

Do not assume a carpet pad roll uses the same coverage or specification as another product. Check the label for roll width, thickness, density, and stated coverage. The calculator estimates area only; follow the carpet manufacturer's and installer's requirements for the selected stair system.

Estimate stair carpet cost

Enter a price per square yard to get a simple carpet material estimate. The calculator multiplies the order area after waste by the price you enter. Make sure the price basis matches the displayed unit and that the supplier is quoting the carpet itself rather than installation or a complete stair package.

A carpet quote may include measuring, removal and disposal of existing carpet, pad, tack strips, stair rods, transition pieces, delivery, labor, and tax. Those items are not included in the optional material total. Ask for an itemized quote if you are comparing products or installation offers.

Stair work can cost more per area than a flat room because every tread and riser takes time to fit. Curves, turns, pattern matching, and specialty edges can also affect labor. Use this calculator for material planning, then confirm the installed price with a qualified carpet professional.

Common stair carpet measuring mistakes

A frequent mistake is measuring only the tread and forgetting the riser. The carpet follows both surfaces, so omitting riser height can leave a large shortage across a full flight. Another mistake is using the floor-to-floor height as the carpet length. The stair surface follows individual treads and risers, and the landing is measured separately.

People also forget landings, count steps incorrectly, or assume both flights have the same width. Count each tread and riser that receives carpet, then check whether the top floor or landing is included in that count. Enter a separate landing depth where carpet continues across a flat platform.

Finally, do not treat square-yard area as an exact roll cut. Carpet width, pattern repeat, seams, and stair wrapping all influence the cut plan. Use the area result as a cross-check, and ask the installer to verify the final quantity before ordering.

When this calculator is useful and its limits

A stair carpet estimator is useful when budgeting a replacement, comparing carpet options, planning a runner, or checking a supplier measurement. It gives a consistent area calculation from the stair dimensions you provide and shows the effect of waste. It can also help you explain your dimensions when asking for a preliminary quote.

It cannot inspect the staircase, create a professional carpet template, calculate a pattern-repeat cut plan, choose a seam location, or determine building code requirements. It assumes repeated step dimensions, matching widths across flights, and rectangular landings of the entered depth. Curved and winder stairs need individual measurements.

Measure carefully and confirm the quantity, carpet direction, padding, and installation method with the product supplier or installer. Stair carpet is a finish material; secure installation and suitable products matter for safe use. Follow the carpet maker's instructions and any local requirements for stairs.