Carpet Calculator
Square yards of carpet and padding for a room, with waste.
10% plain carpet, 15% for patterns or complex rooms, 20% with stairs.
You need
22.0 sq yd
Waste included. Rooms wider than the 12 ft roll need seams; confirm layout with the installer.
- Padding needed
- 22.0 sq yd
- Floor area
- 180 sq ft
- Area with waste
- 198 sq ft
Estimates only. Verify quantities before ordering.
How this is calculated
Square yards = length x width x (1 + waste) / 9, since one square yard is 9 square feet. Padding matches the carpet area. Broadloom rolls are 12 ft wide, so rooms wider than 12 ft involve seams that can add usage beyond this estimate.
Enter the room dimensions and this calculator converts them into square yards, the unit carpet is priced in, for both carpet and the padding underneath. The waste factor covers seam trimming, squaring the ends, and pattern matching; 10% suits a plain carpet in a simple room, 15% is safer for patterned carpet or rooms with jogs and closets.
Broadloom carpet comes on 12 ft wide rolls (some styles 13 ft 6 in or 15 ft), and that roll width, not just area, decides your real usage. A 13 ft wide room needs a seam and can consume noticeably more than the raw area suggests, while a 12 ft wide room fits a roll perfectly. For rooms wider than the roll, have the installer plan the seam layout before you order.
Carpet for common room sizes
Rows include 10% waste. Padding quantity matches the carpet figure.
| Room size | Carpet | Area |
|---|---|---|
| 10 x 10 ft | 12.2 sq yd | 100 sq ft |
| 12 x 10 ft (bedroom) | 14.7 sq yd | 120 sq ft |
| 12 x 12 ft | 17.6 sq yd | 144 sq ft |
| 15 x 12 ft (living room) | 22.0 sq yd | 180 sq ft |
| 20 x 15 ft (great room) | 36.7 sq yd | 300 sq ft |
Roll width is what drives the waste
Carpet comes off a roll in fixed widths, almost always 12 feet and sometimes 15 or 13 feet 2 inches. That constraint, not your floor area, decides how much you buy. A room 13 feet wide needs either a seam or a full second width with most of it cut away, which is why a room a few inches over a roll width can cost dramatically more per square foot than one just under it.
This is also why carpet is quoted and often sold in square yards rather than square feet: one square yard is 9 square feet, and roll goods have always been traded that way. When comparing prices, make sure both quotes use the same unit, because a number that looks like a bargain per square yard is roughly nine times the per-square-foot figure.
Measure the longest and widest points of the room including doorway thresholds and any closet, then think in terms of how the widths will run. If you have a choice, running the length of the roll along the longest dimension usually minimizes seams. An installer will plan this for you, but understanding it explains quotes that seem disconnected from the floor area.
Seams, pile direction, and where they go
Any room wider than the roll will have a seam, and seams are permanent. Place them running the same direction as the main light source rather than across it, since light raking across a seam highlights it. Keep them out of doorways and main traffic paths, because a seam under repeated foot traffic is where the carpet eventually opens up.
Carpet has a nap, a direction the fibers lean, and every piece in a room must run the same way. Pieces laid with opposing nap read as different shades under the same light even though they came off the same roll, which is one of the most common complaints after a self-installed job. Mark arrows on the back of each piece before cutting and keep them aligned.
Padding, and carpet tiles as an alternative
Padding is not the place to economize, because it determines how the carpet feels and how long it lasts far more than most people expect. For residential rooms, a 7/16 or 1/2 inch pad around 6 to 8 pounds density suits most cut-pile carpets. On stairs and in heavy traffic areas, go thinner and denser rather than thicker: an overly soft pad flexes under the backing and breaks the carpet down at the fold.
Carpet tiles are worth considering for basements, playrooms, and any space where a single ruined patch would otherwise mean replacing a whole room. They install without stretching or a power stretcher, you can lift and replace one tile, and there is no roll width constraint so waste is limited to perimeter cuts. They cost more per square foot and the seams are visible by design, so the trade is convenience and repairability against a seamless look.
Common questions
How many square feet in a square yard of carpet?
Nine. Divide square feet by 9 to get square yards. A 12 x 15 room is 180 square feet, or 20 square yards before waste. Some retailers now price by the square foot instead; the math converts either way.
How much extra carpet should I order?
10% beyond the measured area for plain carpet in a simple room, 15% for patterned carpet (repeats must match at seams) or rooms with closets and jogs, and about 20% when carpeting stairs, which eat roughly 2.5 square feet per step on a standard staircase.
Do I need new padding?
Almost always, yes. Padding compresses to the old carpet's traffic patterns, and worn pad makes new carpet feel dead and wear faster. Most carpet warranties require new pad of a specified density, typically 6 to 8 lb rebond for residential use.
How do seams affect how much carpet I need?
Carpet must run the same direction on both sides of a seam, so a room wider than the 12 ft roll needs a second piece cut from the roll's length, often leaving a large unusable strip. That is why installers measure and plan a seam diagram; for wide rooms, expect real usage above the simple area math.