How much carpet do you need? Roll-width optimizer, seam planner, stairs mode, pattern matching & cost estimator.
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Carpet is sold off a roll, so a carpet area calculator has to think in strips, not just length × width. This carpet calculator follows the same method professional installers use:
n with n × roll width − (n−1) × seam overlap ≥ room width. A 12 ft wide room on a 12 ft roll needs 1 strip (seamless); a 13 ft room needs 2 strips with one seam.| Roll width | Common in | Best for |
|---|---|---|
| 12 ft (3.66 m) | US, UK | Rooms up to 12 ft wide; usually the cheapest per yard |
| 15 ft (4.57 m) | US, UK | Wide rooms up to 15 ft — fewer seams |
| 4.0 m (13 ft 1 in) | EU, AU | Often the least-waste pick for ~13 ft rooms |
| 5.0 m (16 ft 5 in) | EU, AU | Very wide rooms; seamless up to 16.4 ft |
Set the roll selector to Auto and the optimizer compares all four widths for your exact room — whether you use this carpet calculator in meters or in feet — the winner is often surprising (a 4 m roll beats 15 ft for a 13 ft room).
To calculate carpet on stairs, each step needs tread depth + riser height + about 1.5 in (3.8 cm) for the nosing. Multiply by the stair width and the number of steps, then add the landing as a small rectangle. The Stairs tab above does this, including pattern-repeat rounding per step and an optional landing.
Carpet is priced per square yard in the US (1 sq yd = 9 sq ft), per square meter in most metric countries, and per gaj in India and Pakistan (1 gaj = 1 sq yd). Results above are shown in all units, and the cost estimator works per square yard or per square meter — pick whichever your shop quotes.
People use this carpet amount calculator in many ways: to calculate carpet on a roll before visiting the shop, as a carpet budget calculator that turns a per-yard quote into a total project price, and as a carpet buying calculator that tells you exactly what to order so you never run short mid-installation. If you are comparing quotes, this carpet calculator cost per square foot view sits right next to the per-square-yard price.
As a carpet area calculator in meters, switch to Metric — a 4 × 3 m room is 12 m². As a carpet area calculator square feet mode, switch to Imperial — a 12 × 12 ft room is 144 sq ft. This carpet calculator feet to yards conversion is automatic: divide square feet by 9, or just read the square-yard result.
The carpet area to gaj calculator readout helps buyers in India and Pakistan (1 gaj = 1 sq yd). The carpet area to var calculator is the same figure — var (vara) is another name for the gaj. This carpet calculator Australia and carpet calculator Canada friendly tool works in metric with 4 m / 5 m roll widths, and in feet/inches with 12 ft / 15 ft rolls for the US, UK and Ireland.
Wondering how much carpet for 12x12 room? About 18–19 sq yd with waste — see the FAQ below for the full breakdown. Use the Stairs tab as your carpet calculator for stairs and landing — one place for the full staircase math. For hallways, the runner calculation doubles as a rough carpet binding calculator guide: binding (the stitched edge finish) is priced per linear foot of runner edge, so note your total runner length from the result above.
Keep every strip's pile direction the same or seams will show as shade bands — the seam planner assumes consistent direction. For patterned carpet, always enter the pattern repeat: each strip is rounded up to whole repeats, which is where most DIY estimates run short. The planner also shows seam positions measured from the wall so you can keep joins out of doorways and high-traffic lanes.
A 12x12 room is 144 square feet, which is 16 square yards. With a standard 12 ft carpet roll you need 1 seamless strip: 12 ft + 4 in trim = 12.33 ft long, so you buy 148 sq ft (16.4 sq yd). Add 10% waste for cutting and mistakes and you should order about 18 to 19 square yards. Enter 12 x 12 above with your roll width to get the exact figure.
Measure one step: tread depth + riser height + about 1.5 in for the nosing. Multiply by the stair width and the number of steps, then add the landing as a small rectangle. Example: 13 steps with an 11 in tread, 7 in riser and 1.5 in nosing on a 36 in wide staircase = 19.5 in per step × 13 steps × 36 in = 63.4 sq ft, plus a 3x3 ft landing (9 sq ft) = 72.4 sq ft, or about 8.9 sq yd with 10% waste. Use the Stairs tab above for the exact math.
In the US and UK, carpet rolls are typically 12 ft (3.66 m) or 15 ft (4.57 m) wide. In metric markets the standards are 4.0 m and 5.0 m. Wider rolls mean fewer seams but can create more waste in narrow rooms — the optimizer above compares all four widths and recommends the one with the least cutting waste for your room.
As a rule of thumb: 5–10% waste for simple rectangular rooms, 10% for stairs, 10–15% for patterned carpet (pattern matching eats extra), and 15–20% for L-shaped rooms, diagonals or rooms with many doorways. The calculator separates cutting waste (from strips and seams, computed exactly) from the contingency waste percentage you add on top.
One square yard = 9 square feet. Carpet in the US is usually priced per square yard, so divide your square footage by 9. A 12x12 room (144 sq ft) is 16 sq yd before waste.
Divide square feet by 10.764 to get square meters, or multiply square yards by 0.8361. The calculator shows results in square feet, square yards, square meters and gaj automatically — just switch between Metric and Imperial above.
A seam is where two strips of carpet are joined. You need a seam whenever the room is wider than the carpet roll — e.g. a 20 ft wide room on a 12 ft roll needs 2 strips with one seam. The seam planner above shows exactly where each seam falls (measured from the wall) so you can plan to keep seams out of high-traffic areas and under furniture.
With patterned carpet, every strip must start at the same point in the pattern, so each strip's cut length is rounded up to a whole number of pattern repeats. Enter the vertical pattern repeat (printed on the carpet sample) and the calculator rounds up — e.g. a 12.33 ft cut with a 24 in repeat becomes 14 ft per strip. This is the step most basic calculators skip and the most common reason DIY installers run short.
A gaj (also spelled guz, and related to the var/vara) is a South Asian unit equal to 1 square yard — 9 square feet or 0.8361 square meters. Carpet in India and Pakistan is commonly sold per gaj. The calculator reports gaj alongside square yards, so a 16 sq yd room is also 16 gaj.
Padding (underlay) is strongly recommended: it extends carpet life, improves comfort and insulation. Order padding for the room area (not the strip area — padding is cut to fit the room, seams don't matter), plus the same waste percentage. Toggle 'Include underlay' above and the cost estimator adds it per square yard or per square meter.
Installation typically runs $3 to $8 per square yard for labor alone (more for stairs, pattern matching or furniture moving), on top of the carpet and padding material. Enter your local per-square-yard rates above and the cost estimator breaks down material, padding and installation separately.
Split the L into two rectangles, measure each, and add them as separate rooms with the 'Add room' button above — the calculator totals everything into one project. Each rectangle gets its own optimal strip layout, which is more accurate than treating the L as one big rectangle.
Carpet pile leans one way, and two strips laid in opposite directions will show a visible shade difference at the seam — even with identical carpet. Always lay all strips with the pile running the same direction (usually toward the main light source or entrance). The seam planner assumes consistent direction.
Measure the hallway length plus trim, and use a runner width (typically 27 in / 70 cm or 36 in / 90 cm). A 12 ft hallway at 36 in wide needs about 4.4 sq yd before waste. For long hallways, pattern repeat matters more — enter the repeat above so each runner section aligns.
It depends on your room width. A 15 ft roll avoids seams in rooms up to 15 ft wide but wastes more in narrow rooms; a 12 ft roll is often cheaper per yard and wastes less under 12 ft. Surprisingly, metric 4 m rolls can beat both for rooms around 13 ft wide. Set the roll selector to Auto above and the optimizer compares all widths and picks the least waste for your exact room.
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