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Carpet Calculator

Convert room dimensions to square yards, roll cuts and padding for wall-to-wall carpet.

Carpet Calculator

Square yards (m²) of carpet to order from a roll, plus underpad, tack strip and seam tape.

How this is calculated

For each room the shorter side is laid across the roll width if it fits; otherwise extra strips are added. Each strip gets a 6 in trim allowance, plus a pattern-repeat allowance for each extra strip.

Enter up to three rooms and your carpet roll width. The calculator finds the best way to cut each room from the roll (adding trim and pattern-match allowances), then totals carpet, waste, underpad, tack strip, seam length and cost.

Results are estimates for planning purposes only. Real-world quantities depend on site conditions, materials and workmanship. Always verify measurements, follow local building codes and confirm quantities with your supplier or a qualified professional before ordering or building.

About the Carpet Calculator

Carpet is priced by the square yard and sold off 12-foot-wide rolls, which makes estimating different from every other flooring type. This calculator converts room dimensions into square yards, plans the roll cuts and seam placement, and estimates padding. It handles bedrooms, living rooms, stairs and hallways, including the extra waste patterned carpets need for matching.

How to use

  1. Enter the room length and width in feet, measuring into doorways and closets where carpet runs continuously.
  2. Enter the roll width — 12 feet is standard, though some carpets come 15 feet wide.
  3. Note rooms wider than the roll: they need a seam, and the calculator plans cuts to minimize them.
  4. Tick patterned carpet if yours has a pattern — matching at seams wastes about one extra repeat per cut.
  5. Include padding: it is sold by the square yard too, and the calculator adds it automatically.

Understanding your results

Square yards are what the carpet store prices against — square feet divided by 9. The roll-cut plan shows how many lengths to cut and where seams fall, so you can verify the layout before ordering. Padding matches the carpet area, with the cutting allowance already included.

How the calculation works

Room area divided by 9 gives square yards, plus a 10 percent cutting allowance — more for patterned carpet, where each seam wastes one pattern repeat. Roll cuts divide the room width into 12-foot roll widths: a 15-foot-wide room needs one full 12-foot cut plus a 3-foot fill strip, seamed together. Padding equals the carpet square yardage.

Carpet Calculator FAQs

It is a long-standing industry convention from when carpet was woven on wide looms — pricing per square yard (9 square feet) stuck. To convert, divide your square footage by 9: a 12×15 room is 180 square feet, or 20 square yards. The calculator does this automatically and adds the cutting waste installers expect.
Order 10 percent extra for standard rooms, and more for patterned carpet, stairs, or rooms with angles and nooks. Patterned carpet wastes an extra pattern repeat — often 12 to 24 inches — at every seam for matching. Keep a remnant after installation: it is perfect for patching a damaged spot or binding into a small rug.
Yes — always install new padding with new carpet. Old padding is compressed, holds dust and odors, and voids most carpet warranties. A 7/16-inch, 6 to 8 pound rebond pad is the standard residential choice: it extends carpet life by years and makes it feel noticeably better underfoot. Padding costs a fraction of the carpet but delivers much of the comfort.
Eight to 15 years depending on quality, traffic and maintenance. Nylon and triexta fibers outlast polyester in busy areas. Regular vacuuming and professional cleaning every 12 to 18 months can push carpet to the top of that range, while skipping padding or buying the cheapest pad shortens it dramatically.
Measure one tread plus one riser as a single unit — typically about 18 to 20 inches — and multiply by the number of steps and the stair width. Most stairs need a 3-foot-wide runner cut from the 12-foot roll. Add 10 to 15 percent waste for stairs since each step needs precise cuts, and plan for extra if the carpet has a pattern to match.
Nabil Sharif, founder of CalcDune

Written by

Nabil Sharif

Founder of CalcDune — a free library of 137 online calculators for finance, health and everyday math. Every calculator shows the formula behind its result, so you can see exactly how your numbers are worked out.

More articles by Nabil →

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