Carpet Calculator: Square Yards, Rolls and Cost by Room Size

1. Measure the length and width of your room in feet and enter them above.
2. Set the waste allowance. Ten percent is standard for simple rectangular rooms; use 15 percent for stairs or patterns.
3. Confirm the roll width. Most residential carpet comes on 12-foot-wide rolls.
4. Optionally enter carpet cost per square yard and pad cost per square foot for a price estimate.
5. Read your results: carpet in square yards, linear feet of roll, number of seams and total cost.

A carpet calculator converts room measurements into the quantity of carpet, padding and roll length you need to buy. It accounts for the standard roll width so you know exactly how many runs of carpet cover the floor and whether seams are required.

Carpet is sold by the square yard in most of North America. A room measured in feet must be divided by nine to get square yards. The calculator does this conversion automatically, adds your chosen waste percentage and works out the linear feet of roll from the roll width and room dimensions.

For other flooring and construction estimates, see the construction calculators hub.

The calculator uses straightforward rectangle geometry and a roll-width formula to determine carpet quantities.

1. Multiply room length by width to get the floor area in square feet.
2. Divide by 9 to convert to square yards.
3. Multiply by the waste factor (1.10 for 10 percent waste) to get the carpet you need to buy.
4. Divide the room width by the roll width and round up to find how many runs are needed.
5. Multiply the room length by the number of runs for the total linear feet of roll.
6. Subtract one from the number of runs to count the seams.

Why Roll Width Matters

Standard carpet rolls are 12 feet wide. If a room is 12 feet wide or narrower, one run of carpet covers the width with no seam. If the room is wider than 12 feet, you need a second run and at least one seam. The seam should run along the length of the room, parallel to the main light source when possible, to make it less visible.

Example 1: Standard Bedroom (15 X 12 Ft)

Area: 15 x 12 = 180 sq ft = 180 / 9 = 20 sq yd.

With 10% waste: 20 x 1.10 = 22 sq yd.

Roll runs: Width 12 ft divided by roll width 12 ft = 1 run. Linear feet = 15 x 1 = 15 linear ft. No seam needed.

Example 2: Living Room (20 X 15 Ft)

Area: 20 x 15 = 300 sq ft = 300 / 9 = 33.33 sq yd.

With 10% waste: 33.33 x 1.10 = 36.67 sq yd.

Roll runs: Width 15 ft divided by roll width 12 ft = ceil(1.25) = 2 runs. Linear feet = 20 x 2 = 40 linear ft. One seam required along the room length.

Example 3: with Costs

Using Example 1 (22 sq yd) at $25 per sq yd for carpet and $0.50 per sq ft for pad:

Carpet cost: 22 x $25 = $550. Pad cost: 198 sq ft x $0.50 = $99. Total: $649.

One square yard equals exactly 9 square feet (3 ft x 3 ft). This conversion is essential when buying carpet because most suppliers price carpet by the square yard.

To convert, divide square feet by 9. To go the other way, multiply square yards by 9.

Carpet rolls come in fixed widths, and the roll width determines whether your room needs seams.

Seam Placement Tips

• Run seams parallel to the primary light source (usually the largest window) so they are less noticeable.
• Avoid placing seams in high-traffic areas like doorways or hallway centers.
• Professional installers use seam tape and a seaming iron for a clean bond.
• Patterned carpet requires extra material for pattern matching at the seam.

The waste allowance covers material lost to cuts, fitting around obstacles and trimming at walls. The right percentage depends on room shape and carpet pattern.

When in doubt, round up. Leftover carpet can cover closets or serve as a spare for future repairs.

Carpet pad (also called underlay or cushion) goes between the subfloor and the carpet. It extends the carpet life, improves comfort and adds sound insulation.

Common Pad Types

• Rebond (bonded urethane): The most popular type. Look for 6 to 8 pound density for residential use.
• Memory foam: Softer feel underfoot; good for bedrooms.
• Fiber pad: Made from natural or synthetic fibers; firm and durable.
• Rubber pad: Very durable; often used in commercial settings.

Pad Thickness

Most carpet warranties require pad no thicker than 7/16 inch for cut pile and 3/8 inch for loop or Berber styles. Too-thick padding can damage carpet backing.

The pad area matches the carpet area, including the waste allowance. The calculator computes this automatically.

Rectangular Rooms

Measure the longest wall for the length and the perpendicular wall for the width. Round each measurement up to the nearest half foot.

L-shaped Rooms

Break the L into two rectangles. Measure each rectangle separately, calculate each area, and add them together. Use a 12 to 15 percent waste allowance for the extra cuts.

Multiple Rooms

Measure each room individually. If the rooms connect with a continuous carpet run, the installer may need longer rolls, so add the lengths rather than treating them as separate orders. For separate rooms, calculate each and sum the total.

Stairs

Measure one stair tread depth plus one riser height, multiply by the stair width and the number of stairs. A landing is a separate rectangle. Add 15 to 20 percent waste for the many cuts involved.

Several factors beyond basic room dimensions change how much carpet you need to order.

Room Shape

Rectangular rooms are the most efficient. L-shaped rooms, alcoves and bay windows create more offcuts and push the waste allowance higher.

Carpet Pattern and Pile Direction

Patterned carpet must be matched at every seam, which can waste a significant amount of material. Directional pile (cut pile, velvet) must run the same way in every piece, limiting how you can rotate offcuts.

Roll Width

A wider roll can eliminate a seam in borderline rooms. Switching from a 12-foot to a 15-foot roll sometimes saves material even though the roll costs more per yard.

Doorways and Transitions

Carpet must tuck into transitions at doorways, which adds a few inches per opening. Multiple rooms with continuous carpet increase the total length of the run.

Furniture and Built-ins

Carpet goes wall to wall, under furniture. Do not subtract furniture footprints from the area unless a permanent built-in will never be moved.

Carpet prices vary widely by fiber type, construction and brand. The table below shows typical price ranges per square yard. Enter your actual price in the calculator for an accurate estimate.

Installation labor adds roughly $3 to $6 per square yard for basic rooms and more for stairs or complex layouts. Pad cost is separate, typically $0.30 to $0.60 per square foot.

Planning a New Carpet Installation

Before visiting a carpet store, use the calculator to know how many square yards you need. This prevents over-ordering and helps you compare quotes accurately.

Budgeting a Remodel

Enter the carpet and pad prices you have been quoted. The total cost estimate lets you compare carpet against other flooring options like tile or hardwood before committing.

Comparing Roll Widths

Try different roll widths (12, 13.5, 15 feet) to see which one eliminates seams in your room. Fewer seams mean a cleaner look and less installation time.

Estimating for Multiple Rooms

Run the calculator once per room and add the totals. This gives a project-wide material list you can hand to an installer.

1. Forgetting Waste Allowance

Ordering the exact room area in square yards leaves nothing for cuts and fitting. Always add at least 10 percent.

2. Measuring to Furniture, Not Walls

Carpet runs wall to wall. Measure the full room, not just the visible floor. Furniture will be moved during installation.

3. Ignoring Roll Width

Ordering square yards without considering the roll width can mean unexpected seams. Check whether your room width exceeds 12 feet.

4. Confusing Square Feet with Square Yards

Carpet is priced per square yard (9 sq ft), not per square foot. Mixing the two up multiplies the cost estimate by nine in the wrong direction.

5. Skipping the Pad

Carpet pad is not optional. It extends carpet life, adds comfort and is usually required to keep the carpet warranty valid.

The geometry in this calculator is exact for rectangular rooms. Cost estimates use the prices you enter and are not authoritative.

Multiply room length by width in feet to get square feet, divide by 9 for square yards, then add 10 percent for waste. A 12 x 15 foot room is 180 sq ft or 20 sq yd; with waste, buy 22 sq yd.

Divide the square footage by 9. One square yard is 3 feet by 3 feet, so 9 square feet. For example, 300 sq ft divided by 9 is 33.33 sq yd.

Most residential carpet rolls are 12 feet wide. Some manufacturers offer 13.5-foot or 15-foot widths, which can help avoid seams in wider rooms.

Use 10 percent for simple rectangular rooms, 12 to 15 percent for L-shaped or irregular rooms, and 15 to 20 percent for patterned carpet or stairs.

A seam is needed whenever the room width exceeds the carpet roll width. With a standard 12-foot roll, any room wider than 12 feet requires at least one seam.

Break the L into two rectangles, calculate each area separately and add them. Use a higher waste allowance of 12 to 15 percent for the extra cuts.

Yes. Carpet pad covers the same area as the carpet, including the waste allowance. The pad goes down first, then the carpet is stretched over it.

Prices vary widely by material and quality. Budget options start around $10 to $15 per sq yd, mid-range is $20 to $40, and premium carpet can be $50 or more. Enter your price above for a specific estimate.

Area is the floor coverage in square yards. Roll length (linear feet) is how many feet of the roll you need to unroll, based on how many runs of the roll width cover the room.

Only if the room width is equal to or less than the roll width. For a standard 12-foot roll, rooms up to 12 feet wide can be carpeted in one piece with no seams.

• Carpet and Rug Institute - Measuring for Carpet (Industry standard for carpet measurement and installation planning).
• Shaw Floors - How to Measure for Carpet (Manufacturer guidance on measuring rooms, roll widths and waste allowance).
• Home Depot - Carpet Buying Guide (Retailer guide covering square yard conversion, padding and installation basics).