Carpet Calculator

Enter the room and roll width to get the length to order, including unavoidable seams.

Room
Carpet roll

Carpet comes off a fixed-width roll. 12 ft is the dominant US standard; 13 ft 6 in and 15 ft are sold as wide goods but are less common, and 6 ft is mostly a commercial and hallway width. You pay for the full width of whatever length you order, so the roll width decides your real waste.

Cost (optional)

Carpet is usually priced per square yard. There are 9 square feet in a square yard.

What to buy

How this calculator works
strips      = ceil(room width ÷ roll width)
roll length = strips × room length
you pay for = roll length × roll width

The room is tried both ways round and the cheaper layout wins — turning a room 90° often drops a whole strip. A 13 ft × 24 ft room takes 312 sq ft of carpet laid one way and 576 sq ft laid the other, on the same roll.

Anything wider than the roll needs a seam. Seams are normal and a good installer hides them, but you should know before you order how many you're getting and roughly where they land.

This figure is the carpet itself. Padding, tack strip and fitting are quoted separately, and patterned carpet needs extra for matching the repeat — ask your supplier for the pattern repeat and add that to the length.

Frequently asked questions

Is carpet sold by the square foot or the square yard?

Broadloom carpet is traditionally sold by the square yard in the US and many suppliers still quote that way, though some now price per square foot. There are 9 square feet in a square yard, so carpet at $27 per square yard is $3 per square foot. This calculator shows both so you can compare quotes directly.

What width does carpet come in?

12 ft is the dominant US standard. 13 ft 6 in and 15 ft exist as wide goods but are stocked less widely, and 6 ft shows up mainly in commercial ranges and hallway runners. Metric equivalents are 3.66 m, 4 m and 5 m.

Why does 13 ft 6 in carpet exist?

To avoid a seam in rooms that just miss 12 ft. A room 12 ft 6 in wide needs two strips and a seam on a 12 ft roll, but goes down in one piece on a 13 ft 6 in roll. If your room is between 12 and 13 ft 6 in, ask whether the carpet you like comes in the wider width before accepting a seam.

How much carpet do I need for a 13 x 12 room?

On a 12 ft roll, run the strips along the 12 ft side: one 12 ft wide strip 13 ft long gives you 156 sq ft with no seam. Run them the other way and you need two strips, 288 sq ft, and a seam. Same room, same roll, nearly double the carpet — which is why this calculator checks both orientations.

Why does my room need a seam?

Because it is wider than the carpet roll in both directions. A 12 ft roll cannot cover a 14 ft wide room in one piece, so the installer joins strips. Seams are a normal part of carpet installation and a good installer makes them nearly invisible — but you should know how many you are getting before you order.

Where should carpet seams be placed?

Run them in the same direction as the light from the main window, so the pile shading hides the join. Keep them out of doorways, entry sightlines and high-traffic paths, and never put one down the middle of a walkway or under dining chairs that slide. Under furniture and at door thresholds are the natural places to hide them. If the installer is also laying pad, its seams should run perpendicular to the carpet seams or be offset by at least 6 inches.

Does the estimate include padding and fitting?

No. This is the carpet itself. Padding, tack strip, door bars and labour are quoted separately, and padding is priced per square foot of floor area rather than per roll length. Installers also trim a few inches off each strip, so treat the roll length as a minimum and let your supplier add their own allowance.

What about patterned carpet?

Patterned carpet needs extra length so the repeat lines up across seams and along walls. Ask your supplier for the pattern repeat measurement and add roughly one repeat per seam. Plain and textured carpets do not have this problem.

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