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Stair Carpet Calculator

Construction

Calculate how much carpet you need to cover a staircase, including treads and risers. Enter step count and dimensions to get square feet and square yards.

Reviewed by the thecalcu.com team · Last updated July 5, 2026

140
2460
816
48

Carpet Needed

58.5
Carpet Needed
6.5

This calculator computes your Carpet Needed, Carpet Needed from the values you enter.

Inputs
Number of StepsStep WidthTread DepthRiser Height
Outputs
Carpet NeededCarpet Needed

What is a Stair Carpet?

A Stair Carpet Calculator determines how much carpet material is needed to cover a staircase, accounting for both the horizontal tread and vertical riser surfaces on each step. Unlike a flat floor area calculation, stair carpeting covers two surfaces per step, which makes manual estimation more error-prone than it first appears.

The calculator converts your step count and dimensions directly into both square feet and square yards, since carpet is commonly priced in the latter unit. If you're finishing other parts of a stairway project, the Ramp Calculator and Decking Calculator cover related sloped-surface and material planning.

Why Use a Stair Carpet Calculator?

Manually calculating stair carpet area means remembering to include both the tread and riser for every step, then summing across the full staircase, a repetitive calculation that's easy to make small errors in in, especially for staircases with many steps. This calculator computes the total instantly and in both common carpet units.

It's also useful for comparing material costs against different step counts or dimensions, such as when evaluating whether reducing riser height (and adding steps) changes total carpet needed for a given total rise.

Who Should Use This Calculator?

Homeowners re-carpeting a staircase use this calculator to get an accurate material estimate before shopping for remnants or ordering carpet. Flooring contractors and installers use it to quickly quote stair carpeting jobs for customers. Interior designers use it when specifying stair coverings as part of a broader renovation project. Property managers budgeting for stairwell carpet replacement in multi-unit buildings use it to estimate costs across several similar staircases. Real estate flippers use it to budget stair carpet replacement as part of pre-sale renovation costs.

What Insights Does the Stair Carpet Calculator Give You?

The Carpet Needed (sq ft) result is the primary figure, the total tread-and-riser surface area across your entire staircase, in square feet. The Carpet Needed (sq yd) result converts that same total into square yards, the unit most carpet retailers use for pricing and ordering. Having both units available means you can quickly compare quotes regardless of how a supplier presents their pricing, without doing the conversion math yourself.

How to use this Stair Carpet calculator

  1. Enter the Number of Steps in your staircase.
  2. Enter the Step Width in inches (reduce this if calculating for a narrower runner rather than full-width carpet).
  3. Enter the Tread Depth in inches, the horizontal surface where you step.
  4. Enter the Riser Height in inches, the vertical face of each step.
  5. Review the Carpet Needed results in both square feet and square yards to compare against supplier quotes or remnant sizes.
Show formula & methodology ↓Show less ↑

Formula & Methodology

The calculator sums the tread-plus-riser area across all steps:

Carpet per Step = ((Tread Depth + Riser Height) × Step Width) ÷ 144

Total Carpet (sq ft) = Carpet per Step × Number of Steps

Total Carpet (sq yd) = Total Carpet (sq ft) ÷ 9

Worked example: For a 13-step staircase with 36 in step width, 11 in tread depth, and 7 in riser height:

Carpet per Step = ((11 + 7) × 36) ÷ 144 = (18 × 36) ÷ 144 = 648 ÷ 144 = 4.5 sq ft

Total Carpet (sq ft) = 4.5 × 13 = 58.5 sq ft

Total Carpet (sq yd) = 58.5 ÷ 9 ≈ 6.5 sq yd

Frequently Asked Questions

How much carpet do I need for stairs?
Stair carpet needs are calculated per step by adding the tread depth and riser height (the two surfaces carpet covers on each step) and multiplying by the step width, then summing across all steps. This calculator handles that calculation and converts the total into both square feet and square yards.
Why do I need to include both tread and riser in the calculation?
Carpeted stairs typically cover both the horizontal tread (where you step) and the vertical riser (the face of the step) for a finished look, so both dimensions need to be included in the area calculation for each step rather than just the tread alone.
How is stair carpet sold, by the square yard or square foot?
Carpet is most commonly sold by the square yard, though remnant pieces for stairs are sometimes priced by the square foot, this calculator provides both units so you can compare pricing regardless of how your supplier quotes it.
Should I add extra carpet for pattern matching or waste?
This calculator computes the base area needed to cover treads and risers; for patterned carpet or runners that need to align visually from step to step, add 10-15% extra material to account for pattern matching and cutting waste.
What's the difference between a stair runner and full stair carpeting?
A stair runner covers only a center strip of each tread and riser (commonly 27-36 inches wide) leaving exposed wood or trim on the sides, while full stair carpeting covers the entire step width, this calculator assumes full-width coverage based on your Step Width input, so reduce that input if calculating for a runner instead.
How many steps does a typical staircase have?
A standard residential staircase with an 8-9 foot floor-to-floor rise typically has 13-15 steps, based on a comfortable riser height around 7-7.5 inches, though this varies by home design and local building code requirements.
Does carpet padding affect this calculation?
This calculator estimates carpet material area only, padding (underlayment) is typically purchased separately and cut to the same tread and riser dimensions, so you can use the same square footage figure for padding estimates as a starting point.
Can I use this calculator for a curved or spiral staircase?
This calculator assumes standard rectangular treads and risers found on straight staircases, curved or spiral stairs have wedge-shaped treads that vary in depth across the width, requiring a more detailed per-step measurement rather than uniform tread depth and step width inputs.
How do I use the square yard result when ordering carpet?
Most carpet retailers price and sell by the square yard, so use the Carpet Needed (sq yd) result directly when requesting quotes or ordering remnant pieces for your stair project.
Also known as
stair carpet yardage calculatorhow much carpet for stairsstaircase carpet calculatorstair tread and riser carpet calculatorcarpet for stairs square footage