Carpet Calculator
Estimate carpet area, linear roll length, padding, seam tape, waste and total material cost for a rectangular room.
Default project preview
33.24 yd²
Measured floor area
272 ft²
Waste-adjusted area
299.2 ft²
Underlay order
31.73 yd²
Estimated seams
1
Calculator
Build the material order
Your order will appear here
Enter the project details and calculate a rounded material estimate.
Input and output guide
What each value means
The labels and units below are part of this calculator’s visible methodology. Replace every default with measurements or product data from the actual project.
Room length
Enter this project assumption in ft. The current imperial default is 18 ft.
Room width
Enter this project assumption in ft. The current imperial default is 14 ft.
Closets and extra area
Enter this project assumption in ft². The current imperial default is 20 ft². Minimum: 0.
Waste allowance
Enter this project assumption in %. The current imperial default is 10 %. Minimum: 0. Maximum: 50.
Carpet roll width
Enter this project assumption in ft. The current imperial default is 12 ft.
Carpet price
Enter this project assumption in per yd². The current imperial default is 28 per yd². Minimum: 0.
Underlay price
Enter this project assumption in per yd². The current imperial default is 7 per yd². Minimum: 0.
Seam-tape price per length unit
Enter this project assumption in per ft. The current imperial default is 0.8 per ft. Minimum: 0.
How to read the outputs
Measured floor area
room plus extra area. Default preview: 272 ft².
Waste-adjusted area
10% allowance. Default preview: 299.2 ft².
Underlay order
5% pad allowance. Default preview: 31.73 yd².
Estimated seams
18 ft tape. Default preview: 1.
Carpet cost
entered area rate. Default preview: $930.84.
Total material cost
carpet, pad and seam tape. Default preview: $1,167.38.
Methodology
Transparent calculation
BuildMeter converts every input to a consistent internal unit, applies the selected allowance, and rounds products up to whole purchasable units.
Measured area = room area + extra areas. Order area = measured area × waste factor. Linear roll length = order area ÷ roll width.
Reviewed project guidance
How to use this estimate in a real project
Last reviewed: July 29, 2026
Use this calculator to estimate carpet area, roll layout and purchase quantity for rooms that must be cut from fixed-width goods. Carpet ordering differs from simple area because seam direction and roll width can create substantial offcuts.
Calculation steps
- 1Measure the longest room dimensions at floor level.
- 2Choose the actual roll width and preferred pile direction.
- 3Lay out full-width strips and identify required seams.
- 4Add pattern or fitting allowance and round to the sold roll length.
Worked numerical example
A 13 ft × 11 ft room has 143 ft² of floor area, but a 12 ft-wide roll may require a 13 ft length plus a seam strip. The purchased area can therefore exceed the room area even before pattern allowance.
Purchasing and rounding
Carpet is often sold by linear length at a fixed roll width. Purchase quantity should follow the strip layout, not only square footage. Pattern repeats may require matching between adjacent pieces.
Interpret the result
The difference between net area and purchased area is layout waste. It is not necessarily an error; fixed roll width and seam placement drive the excess.
Page-specific assumptions
- Rectangular room unless sections are calculated separately.
- One roll width and product.
- Straight seams and consistent pile direction.
- No stairs or complex landings in the room calculation.
Common mistakes
- Ordering only the room square footage.
- Turning one piece against the pile direction.
- Ignoring pattern repeat.
- Placing seams across high-traffic transitions.
Primary and technical references
BuildMeter provides planning estimates, not engineering, architectural, electrical, mechanical, plumbing, permit or code approval. Review the methodology and verify final decisions with product documentation and qualified professionals.
BuildMeter Guides
Understand the measurements and assumptions
Use these visible reference guides before changing project inputs or planning allowances.
FAQ
Carpet Calculator questions
Why does carpet use square yards in the US?+
Carpet is commonly priced by square yard, while rooms are often measured in square feet.
Can carpet be estimated only by floor area?+
Area is a starting point, but roll width and seam layout can create additional waste.
Should closets be entered separately?+
Yes. Add their combined floor area in the extra-area field.