Estimate only. Seams, stairs and patterns change the amount. Ask your installer to measure before you order.
How to use this calculator
Enter the room length and width, pick the width of the carpet roll and choose how much extra to allow. The calculator checks both directions and uses the one that wastes less carpet.
The formula
Strips = room width ÷ roll width (rounded up)
Carpet length = strips × room length
Carpet area = carpet length × roll width × (1 + extra %)
Square yards = square feet ÷ 9
Example: A 15 ft × 12 ft room with a 12 ft roll needs one strip 15 ft long, which is 180 sq ft. With 5% extra you buy 189 sq ft, which is 21 square yards.
What affects how much carpet you need to buy
Carpet is cut from wide rolls, so the amount you buy is often more than the floor area of the room. This calculator figures out how many roll-width strips cover the room, picks the direction that wastes less, then adds your trim allowance. The square yard figure is what most stores use for pricing.
Why roll width matters so much
Take a 14 ft by 18 ft room, which is 252 sq ft. With a 15 ft roll, one strip 18 ft long covers it: 270 sq ft. With 5% extra, you buy about 284 sq ft, or about 31.5 sq yd. With a 12 ft roll, you need two strips no matter which way you run them. The better direction uses two 14 ft strips, which is 336 sq ft. With 5% extra, that becomes about 353 sq ft, or about 39.2 sq yd. Same room, nearly 8 more square yards.
Main factors that change the result
- Room width vs. roll width: A room just wider than the roll creates a large leftover strip.
- Seams: Seam placement and pile direction can force a less efficient layout.
- Patterns: Patterned carpet must line up at seams, so it needs more extra.
- Closets and doorways: Small areas add cuts and can add another strip.
Tips and common mistakes
- Measure at the widest point and add a few inches to each dimension for trimming at the walls.
- Keep seams out of high-traffic paths and away from doorways where possible.
- Run seams toward the main light source so they are less visible.
- Use the offcuts from a large room for closets if the pile direction can match.
- Do not forget padding. It covers the room area, but it is sold separately.
Cost and buying advice
When comparing quotes, make sure each one prices the same thing. Some stores quote carpet only, while others include padding, installation, furniture moving, old carpet removal and stairs. Multiply the square yards by the price per square yard for the carpet alone, then add the other items. Ask for the installer’s measured seam diagram before ordering, since a professional measure can differ from a simple estimate. Order everything from one dye lot so color matches across seams and rooms.
