Carpet Calculator
How much carpet a room needs in square feet and square yards, with a waste allowance and total cost.
How it works
area = length × width · with waste = ⌈area × (1 + waste%)⌉ · square yards = sq ft ÷ 9 · cost = sq ft × price
Length times width gives the floor area in square feet. A waste percentage is added for cuts, seams and matching, then rounded up because you buy whole material, not a fraction. The square-yard figure (÷ 9) is what many carpet sellers quote in, and the cost uses your price per square foot on the amount you’d actually buy.
Worked example
A 12 × 10 ft room is 120 sq ft. Adding 10% for waste and cuts brings it to 132 sq ft — about 14.7 square yards. At $3.50 per sq ft that’s an estimated $462.00.
Frequently asked questions
Why add a waste allowance?
Rooms are rarely a clean multiple of the roll width, and carpet has a nap direction and sometimes a pattern that must run the same way, so offcuts are unavoidable. 10% covers most rectangular rooms; add more for L-shapes, stairs, or bold patterns that need matching.
Why do stores quote square yards?
Carpet rolls are traditionally sold by the square yard (9 sq ft). Converting both ways lets you check a per-square-yard quote against a per-square-foot one — divide the yard price by 9 to compare them on the same footing.
Does this include closets, stairs or hallways?
No — measure each area separately and add them, since each needs its own cuts. Stairs in particular use more carpet than their flat footprint because of the tread-and-riser wrap, so measure generously.
Related calculators
This calculator is for educational purposes. Double-check important results before acting on them.