Carpet Calculator
Carpet is one of the most common residential flooring materials in the United States and is traditionally sold and priced by the square yard, even though rooms are measured in square feet. This carpet calculator converts your room dimensions to both square feet and square yards, applies a waste factor, and optionally estimates material cost at a price per square yard. For simple rectangular rooms, a 10% waste factor is standard. For rooms with closets, alcoves, or L-shapes, or for rooms where the carpet must be cut at an angle, use 15 to 20%. Carpet is manufactured in 12-foot-wide rolls; for rooms wider than 12 feet, a seam is required. Your carpet installer will advise on the optimal cut direction to minimise waste and place seams in low-visibility locations. The calculator can handle multiple rooms by running it once per room and adding the square yardages, or by entering the total combined area of all rooms in one calculation. For stairs, a rough estimate is 1 to 1.5 square yards per step. Always get at least two installer quotes and ask about carpet pad, installation, furniture moving, and disposal of old carpet as separate line items so you can compare quotes accurately. Buy from the same dye lot for colour consistency across all rooms.
Carpet calculation formula
Room area = Length (ft) x Width (ft)
Area with waste = Room area x (1 + Waste% / 100)
Square yards = Area with waste / 9
Cost = Square yards x Price per sq yd
Worked example: 15 x 12 ft bedroom, 10% waste, $30/sq yd
- Room area: 15 x 12 = 180 sq ft
- With 10% waste: 180 x 1.10 = 198 sq ft
- Square yards: 198 / 9 = 22.00 sq yd
- Cost: 22.00 x $30.00 = $660.00
Carpet calculator: frequently asked questions
How do I calculate carpet in square yards?
Measure the room length and width in feet, multiply them to get square feet, and divide by 9 to convert to square yards (1 sq yd = 9 sq ft). Add a waste factor of at least 10% before dividing. For example, a 15 x 12 ft room = 180 sq ft. With 10% waste = 198 sq ft. In square yards: 198 / 9 = 22 sq yd.
Why is carpet sold in square yards?
Carpet in the United States has traditionally been manufactured and sold in 12-foot-wide rolls, and pricing has historically been in dollars per square yard. This convention persists even though square footage is more intuitive for most consumers. To convert a square yard price to a square foot price, divide by 9. For example, $27 per square yard equals $3 per square foot.
How much waste should I add for carpet?
A standard 10% waste factor works for simple rectangular rooms with few seams. For rooms with alcoves, closets, stairs, or L-shapes, use 15 to 20%. Carpet is cut from a 12-foot-wide roll, so rooms wider than 12 feet will require a seam. The placement of seams can significantly affect waste; a professional carpet installer can advise on the most economical cut direction for your room.
Do I need carpet pad? How much?
Yes, carpet pad (also called underlayment or cushion) is highly recommended under almost all residential carpet. It extends carpet life, improves comfort underfoot, and provides additional insulation. Carpet pad is measured and priced the same way as carpet, in square yards. You need the same square footage of pad as carpet. Most installers carry and install pad as part of a complete carpet installation package.
What is the difference between carpet pile types?
Cut pile (including plush, Saxony, and textured) carpets have fibres cut at the tips and are the most common residential type. Loop pile (including Berber) carpets have uncut loops and are very durable. Cut and loop carpets combine both. Pile height, density, and fibre type (nylon, polyester, wool, or olefin) affect durability, appearance, and price. For high-traffic areas, choose a denser, shorter pile carpet with nylon or solution-dyed nylon fibres.
Sources
- Carpet and Rug Institute installation standards: carpet-rug.org.
- Floor Covering Installation Contractors Association: fcica.com.
Reviewed by the CalculatorHub team, edited by James Graham, 14 June 2026. See our methodology. Get professional measurements for large or complex rooms.