Carpet Calculator Formula
Understand the math behind the carpet calculator. Each variable explained with a worked example.
Formulas Used
Area (Square Feet)
square_feet = area_sqftArea (Square Yards)
square_yards = area_sqydSq Yards (with waste)
sqyd_with_waste = area_sqyd * (1 + waste_percent / 100)Estimated Material Cost
estimated_cost = area_sqyd * (1 + waste_percent / 100) * price_per_sqydVariables
| Variable | Description | Default |
|---|---|---|
room_length | Room Length(feet) | 15 |
room_width | Room Width(feet) | 12 |
waste_percent | Waste/Overage(%) | 10 |
price_per_sqyd | Price per Sq Yard(USD) | 30 |
area_sqft | Derived value= room_length * room_width | calculated |
area_sqyd | Derived value= room_length * room_width / 9 | calculated |
How It Works
How to Calculate Carpet Needed
Formula
Square Yards = (Length × Width) / 9
Carpet is sold by the square yard in the United States. One square yard equals 9 square feet (3 ft × 3 ft). Add 10% for waste due to seams, pattern matching, and room irregularities. Carpet typically comes in 12-foot wide rolls.
Worked Example
A room 15 ft by 12 ft at $30 per square yard with 10% waste.
- 01Area = 15 × 12 = 180 sq ft
- 02Square yards = 180 / 9 = 20.00 sq yd
- 03With 10% waste = 20 × 1.10 = 22.00 sq yd
- 04Cost = 22.00 × $30 = $660.00
Frequently Asked Questions
How do I convert square feet to square yards?
Divide square feet by 9. For example, 180 sq ft / 9 = 20 sq yd.
How wide is carpet roll stock?
Standard carpet comes in 12-foot wide rolls. Some styles also come in 15-foot widths. Plan your layout to minimize seams.
Does carpet price include installation?
Usually not. Material cost is separate from installation, which typically runs $1-$3 per square foot. Padding costs an additional $0.50-$1.00 per square foot.
Learn More
Guide
How to Calculate Flooring Area and Material Quantities
Learn how to measure rooms and calculate flooring material needed for tile, hardwood, carpet, and laminate. Covers irregular rooms, waste factors, and cost estimation.
Ready to run the numbers?
Open Carpet Calculator