Carpet Calculator
How much carpet do you need? Square yards cut from 12 or 15 ft rolls, number of seams, pad, tack strip and seam tape for any room.
Your estimate
19.3 sq yd
Carpet to order
- Off the roll
- 14.5 ft of 12 ft roll
- Seams
- none
- Room area
- 18.7 sq yd (168 sq ft)
- Offcut waste
- 4%
- Pad
- 19.6 sq yd
Show the math
- Drops run along the room length (14 ft); the roll covers 12 ft across
- Drops = 12 ft ÷ 12 ft → 1
- Each drop = 14 ft + 2 × 3 in trim = 14.5 ft
- Carpet = 1 × 14.5 ft × 12 ft = 174 sq ft ÷ 9 = 19.3 sq yd
- Pad = room area × (1 + 5%) = 19.6 sq yd
Shopping list & cost
| Item | Spec | Qty | Cost |
|---|---|---|---|
| Carpet | 12 ft roll, 1 drop × 14.5 ft | 14.5 ft off the roll = 19.3 sq yd | — |
| Carpet pad (underlay) | room area + 5% | 19.6 sq yd | — |
| Tack strip | 4 ft strips, minus doorways | 49 ft (13 strips) | — |
| Seam tape | hot-melt | none needed | — |
| Transition / door bar | one per doorway | 1 | — |
Prices are what you enter under Advanced options. Estimates only — check stock and pricing with your supplier.
Quick answer A 14 × 12 ft bedroom carpeted from a 12 ft roll needs 19.3 sq yd of carpet (14.5 ft of 12 ft roll, no seams) plus 19.6 sq yd of pad. A 4.5 × 3.9 m room from a 4 m roll needs 18.6 m². Carpet is cut in full-width drops, so the answer depends on the roll width, not just the floor area: square yards = linear feet off the roll × roll width ÷ 9.
Method & assumptions
Drops = Room width ÷ Roll width, rounded up Drop length = Room length + 2 × trim Carpet (sq yd) = Drops × Drop length × Roll width ÷ 9 Seams = Drops − 1; seam length = (Drops − 1) × Room length Pad = Room area × (1 + pad waste %)
- Drop
- one full-width length cut off the roll
- Roll width
- 12 ft, 13 ft 6 in or 15 ft (4 m or 5 m)
- Trim
- extra length at each end for squaring and fitting
Assumptions & limits
- The calculator checks both directions and picks the one that uses less carpet, preferring fewer seams on a tie.
- Offcuts are not re-used as fill pieces. Installers can sometimes seam a narrow fill strip from leftover carpet; that saves carpet but adds a seam.
- Patterned carpet needs extra length to match the pattern at seams — add the pattern repeat per drop.
- Pad comes in rolls about 6 ft wide and is seamed without overlap, so 5% waste is usually enough.
Rounding: purchase quantities are always rounded up to whole units as sold. See our methodology.
Diagram
How to use this calculator
- Measure the room at its longest and widest points, into door openings and closets.
- Pick the roll width your carpet comes in — 12 ft is standard, many styles also come in 15 ft.
- Leave the direction on "whichever uses less" or force the pile to run the way you want; every piece must run the same way.
- Keep the 3 in trim allowance per end — walls are never perfectly square.
- Use the pad, tack strip and seam tape lines as the rest of the shopping list.
Worked examples
Imperial: 15 × 13 ft living room — 12 ft vs 15 ft roll
- 12 ft roll: 15 ÷ 12 → 2 drops × 13.5 ft = 27 ft × 12 = 324 sq ft = 36 sq yd, 1 seam
- 15 ft roll: 1 drop × 13.5 ft = 13.5 ft × 15 = 202.5 sq ft = 22.5 sq yd, no seam
- Room is 21.7 sq yd — the 15 ft roll saves 13.5 sq yd
Metric: 5.2 × 3.6 m bedroom, 4 m roll
- Run along the 5.2 m length: 1 drop × 5.35 m
- 5.35 × 4 = 21.4 m² for an 18.7 m² room, no seam
In depth: carpet planning notes
Why carpet is bought by the roll, not by the room
Broadloom carpet is made in fixed widths — 12 ft is standard in North America, with some styles also in 15 ft or 13 ft 6 in, and 4 m or 5 m in the UK and Australia. The installer cuts full-width "drops" off the roll, long enough to cover the room plus a few inches at each end for trimming. If the room is narrower than the roll, you pay for the full roll width anyway; if it is wider, you need a second drop and a seam. That is why a 13 × 15 ft room uses 36 sq yd from a 12 ft roll but only 22.5 sq yd from a 15 ft roll, even though the room itself is 21.7 sq yd.
The calculator works out both directions and picks the one that wastes less, preferring fewer seams on a tie. Two things it deliberately doesn't do. It doesn't assume offcuts become fill pieces — installers sometimes seam a narrow strip from leftover carpet, which saves material but adds a seam in a place you might not like. And it doesn't account for pattern matching: patterned carpet needs extra length on each drop equal to the pattern repeat so the design lines up across seams. Ask your retailer for the roll width and repeat before you choose.
Pad, tack strip and seams
Pad (underlay) comes in narrower rolls and is butted edge to edge without overlap, then stapled or glued, so it wastes little — the room area plus about 5% is typical. Residential guidelines from the Carpet and Rug Institute call for pad no thicker than 7/16 in and of adequate density; a thick, soft pad can let the carpet flex and wrinkle. Tack strip is nailed around the perimeter, leaving a gap slightly less than the carpet thickness to the wall, and it stops at doorways where a transition strip takes over.
Seams are where carpet jobs look good or bad. Keep them out of doorways and main walkways, run them toward the main light source so the joint casts less shadow, and make sure all pieces have the pile running the same way — a drop turned around reads as a different color. Hot-melt seam tape is laid under every seam; the calculator adds 5% to the seam length. For stairs, count each step separately; a single stair uses a piece about 2 ft long across its width, and the pile should run down the stairs.
Reference table
| Room | Carpet ordered · seams |
|---|---|
| 10 × 10 ft | 14.0 sq yd · 0 (2 ft of the roll width is offcut) |
| 12 × 12 ft | 16.7 sq yd · 0 |
| 12 × 14 ft | 19.3 sq yd · 0 |
| 13 × 15 ft | 36.0 sq yd · 1 — or 22.5 on a 15 ft roll |
| 15 × 20 ft | 41.3 sq yd · 1 — or 34.2 on a 15 ft roll |
Key facts
- 1 square yard
- 9 sq ft (0.836 m²)
- Standard roll widths
- 12 ft and 15 ft (4 m and 5 m)
- Tack strip
- about ¼–⅜ in from the wall; sold in 4 ft strips
- Pad
- sold by the square yard; up to 7/16 in thick, about 6–8 lb density for residential
Tips & common mistakes
- Ask for the roll width before you choose a carpet — a room just over 12 ft wide is far cheaper in a 15 ft roll.
- Keep seams out of doorways and main walkways, and run them toward the main light source so they are less visible.
- Pile direction must match on every piece; most installers have the pile lean toward the room entrance.
- Stairs are measured and quoted separately — ask the installer, because waste depends on the staircase shape.
Frequently asked questions
How many square yards of carpet do I need for a 12 × 12 room?
About 16.7 sq yd from a 12 ft roll: 12.5 ft (with trim) × 12 ft = 150 sq ft ÷ 9. The room itself is 16 sq yd.
How do I convert square feet to square yards for carpet?
Divide square feet by 9. But for carpet, convert the amount cut off the roll, not the room: linear feet × roll width ÷ 9.
Why is my carpet quote more than the room area?
Because carpet comes off a fixed-width roll. A 13 ft wide room on a 12 ft roll needs a second full-width drop for the extra foot, and the trim at each end adds a few percent more.
How much carpet pad do I need?
The room area plus about 5%. Pad is seamed edge to edge without overlap, so it wastes much less than carpet.
What size carpet roll should I choose?
Choose the width that covers the room's narrower dimension in one piece if you can. Rooms up to 12 ft wide fit a 12 ft roll; 12–15 ft rooms usually work out cheaper and seam-free on a 15 ft roll.
How much tack strip do I need?
The room perimeter minus doorways. A 14 × 12 ft room with one door needs about 49 ft — 13 strips of 4 ft.
Sources
- Shaw Floors – Carpet installation planning — accessed : “Most carpet is manufactured in 12-foot rolls, although 15-foot rolls are available as well.”
- Carpet and Rug Institute – CRI 105 Standard for Installation of Residential Carpet — general reference — not cited for a specific figure
- NIST – unit conversion (square yards) — general reference — not cited for a specific figure
Default values (yields, coverage rates and densities) are typical figures from manufacturer literature. Always check the label on the product you buy.
Related calculators
- Flooring CalculatorCalculate boxes of vinyl plank, hardwood or engineered flooring, including a 12×12 room, with layout waste, underlay and baseboard.
- Laminate Flooring CalculatorLaminate-specific estimate: boxes of planks, underlayment rolls and vapor barrier, quarter round, transitions, expansion gap and last-row width.
- Baseboard CalculatorLinear feet of baseboard (skirting) for a room minus door openings, converted to 8, 12, 14 or 16 ft pieces with waste, nails and caulk.
Learn more in our guides
Method, waste and worked examples: Flooring area: waste, boxes and roll width.
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DIYCalcLab. “Carpet Calculator.” Oct 19, 2026. https://diycalclab.com/flooring/carpet-calculator/
Estimates only. Verify quantities with your supplier and local building codes. For structural, electrical or safety-critical work, consult a licensed professional. Full disclaimer.