This carpet calculator totals room or straight-stair coverage in square feet, square yards, and square meters, then separates that coverage from an optional fixed-width broadloom purchase estimate.
Calculate carpet area for one or more rooms
Enter each non-overlapping rectangle as a room or section. The calculator adds coverage and converts the same area into square feet, square yards, and square meters. That first answer is the area being covered. The fixed-width purchase estimate is a separate planning result.
Break an L-shaped room into non-overlapping sections. Do not overlap rows, because overlapping area would be counted twice.
Coverage is length times width. Broadloom purchase area uses full-width drops, trim, and any entered pattern repeat.
The engine uses exact customary and SI relationships from NIST Appendix B. One square yard equals 9 .
Example: carpet for a 10-by-10-foot room
- A 10 × 10 room covers 100 sq ft, 11.11 sq yd, or 9.29 m².
- With a 12 ft roll, 3 in trim at each wall, no repeat, and no added allowance, the engine selects 1 full-width drop cut to 10.5 ft.
- The estimated broadloom purchase area is 126 sq ft.
- That leaves 26 sq ft, or 26%, above floor coverage before pile and seam review.
Read the fixed-width roll estimate
The CRI 105 residential standard calls for at least 3 in at each wall for trimming. The engine adds that margin before counting complete drops. It then rounds drop length for the entered repeat along the roll and compares both room orientations when requested. Compare both is only the lower mathematical result. Pile, traffic, light, doors, and seams can require the other direction.
The 12 ft and 15 ft shortcuts are examples backed by current Shaw 12-foot and Shaw 15-foot products. They are not universal limits. Copy width from the chosen product. A pattern repeat also comes from its specification, as the Godfrey Hirst product page illustrates. No universal waste percentage is added. The separate additional allowance starts at 0%.
Measure carpet for identical straight stairs
Switch to Straight stairs for identical rectangular steps. Enter step count, tread depth, riser height, stair width, and any measured nose or wrap allowance. The engine adds tread, riser, and nose for one step, multiplies that run by the count and width, then adds an optional rectangular landing. Use another method or an installer for winders, curved or pie-shaped steps, caps, and runner layouts.
Estimate carpet and padding material cost
Enter carpet and padding prices in the area basis used by the quote. In room mode, carpet cost uses estimated broadloom purchase area after any additional allowance. Padding cost uses floor coverage, so carpet offcut does not inflate it. In straight-stair mode, the subtotal applies the entered area prices to measured surface coverage only; it does not include roll width, runner cut waste, or a supplier purchase minimum. Labor, tax, delivery, removal, adhesive, and tack strip are outside the result. Entering a positive carpet or pad price fills the coverage-based subtotal and its carpet and padding split, expressed in your entered currency.
Know when the roll estimate needs an installer
Ask for an installer-reviewed cut plan when seam position matters. The calculator cannot see doors, traffic paths, window light, pile direction, horizontal pattern side match, or whether a remnant from one room suits another. CRI 105 treats these as installation decisions and requires adjacent broadloom pieces to share pile direction. Compare both may select a different mathematical orientation for each room, so confirm one compatible direction for adjacent rooms before ordering.
This tool is for wall-to-wall broadloom and scoped straight-stair coverage. Do not use its roll estimate for carpet tile packages, rugs, fixed-width runners, or products whose usable roll length is reduced by a core or damaged ends. The calculator also cannot confirm that the supplier has enough material from one production lot or that the selected roll dimensions are available.
Frequently asked questions
How much would carpet cost for a 20-by-20-foot room?
A 20 × 20 room covers 400 . Under an explicit example with a 12 roll, 3 trim at each wall, no pattern repeat, no added allowance, and a carpet price entered as 3.00 per sq ft, the engine plans 492 of broadloom and returns a 1,476 material subtotal, expressed in the same currency. Replace the example price and product settings with the quote you have; this is not a market-rate estimate.
How much does carpet cost for 2,000 ?
There is no single geometry-independent answer. If the 2,000 is one 50 × 40 rectangle, the same 12 roll and 3 trim assumptions produce 2,424 of planned broadloom. At an explicitly entered carpet price of 3.00 per sq ft, the engine returns a 7,272 material subtotal, expressed in the same currency. Multiple rooms or another roll width can change the full-width drop total.
Why can the carpet purchase estimate be larger than the floor area?
Broadloom is cut in complete full-width drops. Wall trim, unused width beside a drop, pattern-repeat rounding, pile direction, and seam placement can all make purchase area exceed floor coverage. The calculator labels that difference as estimated roll offcut and keeps any user-entered additional allowance separate.
Should carpet padding use the same offcut as broadloom carpet?
No. This calculator reports padding from floor or stair coverage and does not copy broadloom roll offcut into the pad quantity. It is a coverage result, not a padding-roll cut plan, so check the selected pad's package or roll dimensions before buying.