Carpet Patch Size and Material Calculator
Calculate the exact patch dimensions and total carpet material needed to repair a damaged area, including seam allowance and waste factor.
Formulas Used
Patch Dimensions:
- Patch Length = Damage Length + 2 × Seam Allowance
- Patch Width = Damage Width + 2 × Seam Allowance
Patch Area:
- Patch Area (in²) = Patch Length × Patch Width
- Patch Area (ft²) = Patch Area (in²) ÷ 144
Total Material with Waste:
- Total Material (ft²) = Patch Area (ft²) × (1 + Waste Factor / 100)
Strip Length from Roll:
- Strip Length (in) = Total Material (in²) ÷ Roll Width (in)
Cost Estimate (optional):
- Cost = Total Material (ft²) × Cost per ft²
Assumptions & References
- Seam allowance is added equally to all four sides of the damaged area to ensure a secure bond when using carpet tape or adhesive.
- A typical seam allowance is 1 inch per side; professional installers may use 0.5–2 inches depending on carpet pile and backing type.
- The waste/pattern match factor accounts for aligning carpet pile direction and repeating patterns; 10–15% is standard for patterned carpets, 5–10% for plain carpets.
- Standard residential carpet rolls are 12 ft (144 in) wide; commercial rolls may be 6 ft or 15 ft wide.
- All calculations assume a rectangular damaged area. For irregular shapes, use the bounding rectangle dimensions.
- Cost estimate reflects material only and does not include labor, adhesive, seam tape, or other installation supplies.
- Reference: Carpet and Rug Institute (CRI) installation guidelines recommend cutting patches with a sharp utility knife and straightedge for clean seams.