Calculating carpet for 13 stairs and a landing requires precise measurements and allowances for waste and pattern matching. This guide walks through common stair types, step-by-step measurement, sample calculations, and ordering tips so homeowners can estimate the carpet needed with confidence.
| Component | Typical Size | Carpet Needed |
|---|---|---|
| Tread | 10″ Wide | 13 x 10″ = 130″ (10.8 ft) |
| Riser | 7″ High | 13 x 7″ = 91″ (7.6 ft) |
| Landing | 4′ x 4′ | 16 sq ft |
Why Accurate Measurement Matters
Accurate measurement prevents costly shortfalls and excess purchasing. **Stair carpeting is less forgiving than room installations** because seams, pattern repeats, and extra cutting require careful planning.
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Identify The Stair Type
Different stair types change material needs. **Common types include straight-run, L-shaped, U-shaped, and open-riser**; straight-run is simplest to calculate while landings and returns increase waste and seam needs.
Essential Measurements To Take
Measure these elements: **tread depth (front to back), riser height, number of steps, landing length and width, and stair width**. Use a tape measure and record inches to the nearest 1/8″.
How To Measure Each Component
Measure tread depth at the widest usable depth, riser height from top of one tread to top of the next, and stair width from inner to outer nosing. **Measure landing length and width parallel and perpendicular to the steps.**
Standard Stair Measurement Example
For a typical stair with 13 steps: tread depth 10″, riser height 7″, width 36″, and a 4′ x 4′ landing. **These dimensions allow a practical sample calculation used throughout the guide.**
Step-By-Step Carpet Calculation Method
Follow a consistent method: calculate linear footage for treads and risers, convert to square feet or yardage, add landing area, and include waste allowance. **This structured approach reduces errors and accounts for seams and pattern matching.**
1. Calculate Tread Area
Multiply tread depth by stair width by number of treads. Example: 10″ (0.833 ft) x 3 ft x 13 = 32.5 sq ft. **This is the total tread area before adding risers and waste.**
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2. Calculate Riser Area
Multiply riser height by stair width by number of risers. Example: 7″ (0.583 ft) x 3 ft x 13 = 22.8 sq ft. **Risers are often covered but sometimes painted or left exposed—confirm whether they need carpet.**
3. Add Landing Area
Measure landing length and width. Example: 4′ x 4′ = 16 sq ft. **Include any additional small landings or intermediate platforms.**
4. Convert To Carpet Yardage
Carpet is sold by the square yard. Divide total square feet by 9 to get square yards. Example: (32.5+22.8+16)=71.3 sq ft → 7.92 sq yd. **Round up to full yards and account for roll width when planning.**
5. Add Waste And Pattern Repeat
Add 10–20% waste for straight runs; add 15–30% for patterned carpet or complex stairs. Example: 7.92 sq yd + 20% = 9.5 sq yd. **Always round up to the next half or full yard and consider roll widths of 12′ or 15′.**
Accounting For Carpet Roll Width
Roll width affects how seams are cut and how many runs are required. **Common widths are 12′ and 15′; stair widths under the roll width allow single-piece treads for many stairs.**
How Roll Width Influences Waste
If stair width is narrower than the roll width, less seam is needed but landing orientation may require additional cutting. **For narrow stairs, remnants may be used for risers, reducing total yardage.**
Patterned Carpet And Directional Pile Considerations
Pattern repeats and directional nap increase required material. **Matching patterns across treads and landings can raise waste to 25% or more**, so check manufacturer specs and request matching guidance from the retailer.
Sample Calculation For 13 Stairs And A Landing
Using the earlier example: tread area 32.5 sq ft, riser area 22.8 sq ft, landing 16 sq ft. Total 71.3 sq ft = 7.92 sq yd. With 20% waste: 9.5 sq yd. **Round up and purchase 10 sq yd to be safe; for patterned carpet, order 11–12 sq yd.**
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Measuring For Different Stair Scenarios
Stairs vary; **open-riser, winding, and curved stairs need bespoke measurement** and often require specialty installers and extra material for shaping and seams.
Winder Or Curved Stairs
Measure each tread individually, noting varying depths. **Winders and curves usually require 20–40% more material due to irregular shapes and cutting loss.**
Double-Run Or U-Shaped Stairs
Measure both runs and any intermediate landings. **Additional seams and joins will increase waste and may necessitate extra cushion padding pieces.**
Common Mistakes To Avoid
Common errors include under-measuring risers, ignoring pattern repeats, and failing to account for seams. **Always measure twice and allow extra for trimming and errors.**
Padding And Stair Tack Strip Requirements
Padding for stairs differs from room padding; **use denser, lower-profile stair padding (often 1/4″ to 3/8″) to maintain proper fit and avoid trip hazards.** Include extra padding square footage equal to the carpet area plus small waste for cuts.
Installation Options And Their Impact On Material Needs
Different installation methods (carpet runner, full-cover, pre-cut stair treads) change quantities. **A runner uses less carpet but requires borders and may need different padding and underlay.**
Runner Installation
Runners typically cover the center portion of the stairs. **Measure runner width and add edge returns for proper tack and aesthetic—this usually reduces total yardage but may increase cutting waste.**
Full-Cover Installation
Full cover wraps carpet over treads to risers and onto landings. **This method requires the most material but offers a continuous look and better wear coverage.**
How To Order Carpet: Practical Tips
Bring detailed measurements and photos to the retailer. **Specify stair count, tread/riser sizes, landing dimensions, and whether the carpet has a pattern repeat or directional nap.** Ask for a written estimate of yardage and waste percentage used for the quote.
Saving Money Without Sacrificing Quality
Choose a durable carpet grade suitable for stairs, as stairs receive heavy foot traffic. **Mid-range loop or cut-loop blends often provide the best balance of durability and cost.** Purchasing an extra remnant can provide matched dye-lot backup for future repairs.
When To Hire A Professional Installer
Professional installers are recommended for complex stairs, patterned carpets, or when exacting seams are required. **A good installer will verify measurements, recommend padding, and ensure correct seam placement.**
Checklist Before Final Purchase
- Confirm total square yards including waste.
- Verify roll width and pattern repeat details.
- Decide on padding type and thickness.
- Request installer measurement verification if uncertain.
Frequently Asked Questions
How Much Extra Carpet Should Be Ordered For 13 Stairs?
For plain, straight stairs, **add 10–20% extra**; for patterned or complex stairs, **add 15–30%**. Round up to the nearest whole yard to ensure sufficient material and matching dye lot.
Does The Riser Always Need Carpet?
Risers are sometimes left painted or stained for design reasons. **If covering risers, include them in the square footage measurement and consider additional vertical seams.**
Can Remnants Be Used For Stairs?
Remnants can work for narrow stairs or runners if color and pile match and there is enough length. **For full-cover stairs and patterned carpets, remnants are often impractical.**
Quick Reference Table: Typical Yardage Estimates
| Scenario | Estimated Yardage (No Pattern) | Estimated Yardage (Patterned) |
|---|---|---|
| 13 Stairs, 36″ Width, 4’×4′ Landing | 10 sq yd | 11–12 sq yd |
| 13 Stairs, 48″ Width, 5’×5′ Landing | 12–13 sq yd | 14–16 sq yd |
Final Ordering Tips
Confirm dye lot numbers and request that the retailer reserve or label extra material for future repairs. **Keep the receipt and any remnant pieces as they may be needed for patching or warranty claims.**
For precise results, homeowners should measure carefully, include adequate waste, and consult an installer for complex layouts to ensure the correct amount of carpet is ordered for 13 stairs and a landing.