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Carpet Calculator

Carpet isn't sold by the room's area. It's cut from a roll, and you pay for full roll widths. Enter the room size and roll width and get the real square yards to order.

Diagram of carpet roll strips running across a room, with the roll width marked
Carpet comes off a roll (usually 12 ft wide) and is priced by the square yard.

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Enter your measurements

How carpet quantity is calculated

Carpet is priced by the square yard (1 sq yd = 9 sq ft) and most of it is made in 12 ft roll widths, and some styles come 13.5 or 15 ft wide. You can't buy a 14 ft-wide strip from a 12 ft roll: the room is covered in full-width strips, and the offcuts are yours.

The math: strips = room width ÷ roll width, rounded up; material = strips × roll width × strip length. This calculator tries the roll running both directions and uses whichever needs less material. For a 12 × 15 ft room on a 12 ft roll, running the long way needs one 15 ft strip (180 sq ft = 20 sq yd), while the other way needs two strips and 60% more carpet. A waste allowance (10% standard) is added for seams, cuts and pattern matching before converting to square yards.

Good installers can sometimes piece the narrow fill strip from the offcut of the main strip and beat this estimate on simple rooms. Treat the result as the safe order quantity, and confirm the layout with your installer before ordering. Laying hard flooring instead? The Flooring Calculator counts boxes from the same room measurements.

Sources

The figures behind this calculator come from published manufacturer data and industry standards:

Worked examples

12 × 15 ft bedroom, 12 ft roll

One 15 ft strip covers it: 180 sq ft of material, +10% waste.

Buy 22 sq yd of carpet

14 × 14 ft lounge, 12 ft roll

Two strips either way: 336 sq ft of material, +10% waste.

Buy 42 sq yd of carpet

10 × 12 ft office, 15 ft roll

One 10 ft strip of the wider roll: 150 sq ft, +10% waste.

Buy 19 sq yd of carpet

Frequently asked questions

How many square yards of carpet do I need for a 12×15 room?
20 sq yd net. The room is 180 sq ft and a 12 ft roll covers it in one strip. With the standard 10% allowance for seams and cutting, order 22 sq yd.
Why is the carpet I have to buy bigger than my room?
Because carpet comes off a roll of fixed width. If your room is 14 ft wide and the roll is 12 ft, you need two full widths (24 ft of width), and the spare becomes offcut. Choosing a style that also comes in a 15 ft width can cut the waste dramatically.
Is carpet padding included?
No. Pad (underlay) is sold separately, usually by the square yard too. You need roughly the same square yardage as the carpet itself; your installer's quote normally itemises it.
How much extra carpet should I order for waste?
10% is the standard retail allowance for a rectangular room with seams. Add more (15%) for patterned carpet that must match at seams, stairs, or rooms with alcoves and angles.
Does carpet direction matter?
Yes. The pile must run the same way throughout, so fill strips can't just be rotated offcuts. That's why this calculator counts full strips in a single direction rather than assuming offcuts can be flipped.

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Estimate disclaimer: results are planning estimates based on standard manufacturer yields and coverage figures. Site conditions, product choice and installation method change actual quantities. Verify before you buy, and follow local building code for structural work. This tool does not replace professional engineering advice.

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