Carpet Calculator
Estimate the amount of carpet and padding needed for your room flooring project.
How to Calculate Carpet for Your Home
Accurate measurement is the foundation of any successful flooring project. Whether you are DIYing or hiring a contractor, knowing how much carpet you need prevents over-ordering material or, worse, running short mid-installation.
The Basic Carpet Formula
To find the area of a rectangular room, the formula is straightforward:
Length (ft) × Width (ft) = Square Footage
Since most carpet is sold by the square yard in many regions, you simply divide the total square footage by 9:
Square Footage ÷ 9 = Square Yards
Why You Need a Wastage Factor
You should never buy the exact square footage of your room. Carpet usually comes in standard rolls (often 12 or 15 feet wide). Because rooms aren't always perfectly sized to match roll widths, you will have off-cuts and seams. We recommend the following wastage margins:
- 10%: For standard rectangular rooms with minimal obstacles.
- 15%: For rooms with L-shapes, large closets, or alcoves.
- 20%: For stairs, hallways with many doorways, or rooms with irregular angles.
Example Calculation
If you have a bedroom that is 12 feet wide and 15 feet long:
- 12 × 15 = 180 square feet.
- Add 10% for waste: 180 + 18 = 198 square feet.
- Convert to yards: 198 ÷ 9 = 22 square yards.
- If the carpet costs $4.00 per sq ft, your estimated cost is 198 × $4.00 = $792.00.
Measuring Tips
Always measure into the deepest part of doorways to ensure the carpet extends under the door and meets the transition strip. If you have a closet, treat it as a separate rectangle and add its area to the main room calculation before applying the waste percentage.