Carpet Calculator

How to Measure a Room for Carpet

Measure length and width wall-to-wall at the widest points, not at door openings. Include closets as part of the room if they will be carpeted. For irregular rooms, divide into rectangles, calculate each separately, and add the results. Multiply length by width to get square footage. Divide by 9 to convert to square yards, the unit carpet is sold in. Add 10 percent waste for a rectangular room, 15 percent for complex shapes, and 20 to 25 percent for stairs and patterned carpet.

The 12 Foot Roll Rule

Standard carpet rolls come in 12 foot widths. If the shorter dimension of your room is 12 feet or less, you can install the carpet from a single piece with no seam. If it exceeds 12 feet, you will need a seam somewhere — the installer will choose its location to minimize visibility. Rolls in 13'2" and 15 foot widths exist but are less common and more expensive per square yard. Always confirm the roll width with your retailer before ordering, because waste calculations change if the room dimensions and roll width do not match efficiently.

Carpet vs Pad Costs

Carpet is typically priced per square yard, but the total installed cost includes carpet, padding, and labor. Padding runs 7 to 15 dollars per square yard depending on density and thickness — 8 lb rebond is standard for living areas, 6 lb for bedrooms, and higher-density 10 lb for stairs and heavy traffic. Installation runs 5 to 10 dollars per square yard. For a 20 sq yd room, expect 300 to 700 dollars carpet, 140 to 300 dollars padding, 100 to 200 dollars install, plus 50 to 100 dollars for old carpet removal — roughly 600 to 1,400 dollars total.

Choosing a Carpet Fiber

Nylon is the most durable synthetic fiber, resistant to wear and crushing. It is the default for high-traffic homes and costs a bit more than polyester. Polyester (PET) is softer, stain-resistant, and cheaper but crushes faster. Triexta is a newer polyester variant with better crush resistance. Wool is the premium natural fiber — soft, durable, and expensive. For stairs and hallways, nylon or wool; for bedrooms, polyester is perfectly acceptable and saves money. Avoid olefin (polypropylene) for anything except low-traffic basement installations.

Frequently Asked Questions

How many square yards in a square foot?

1 square yard = 9 square feet.

What's a good waste percentage?

10% for simple rooms, 15% for complex shapes, 20-25% for stairs and patterned carpet.

Do I need to replace the pad?

Yes — pad wears out with the carpet. Installing new carpet over old pad voids the warranty and feels flat.

Can I install carpet myself?

Technically yes, but it requires a power stretcher and a seam iron. Most warranties require professional installation.

How long does carpet last?

5 to 15 years depending on fiber, traffic, and quality. Nylon in a bedroom can last 20+ years.