Carpet Calculator

Calculate carpet square yards, roll lengths, and seams for 12-foot and 15-foot broadloom rolls. Estimate padding, tack strips, and optional stair steps with realistic waste allowances.

Reviewed and updated September 26, 2026

Use it when you want to know

Roll width and seam detectionFlags rooms wider than standard rolls and accounts for consistent pile direction.
Square yards and square feetConverts floor area to square yards (divide by 9) for straightforward retail quotes.
Padding and installation suppliesCalculates cushion rolls, perimeter tack strip sticks, and transition bars.

Calculator

How much carpet do you need to buy?

Enter your room dimensions to see exact square yards, square feet, roll cuts, and seam advice. Expand the optional sections to include stairs, cushion padding, or project costs.

1. Project dimensions

How do you want to enter the area?

Add rooms (Seam-aware)I know total sq ft

Rooms to carpet

Enter length and width for each area. The tool checks roll orientation to minimize seams.

2. Carpet roll and waste allowance

Carpet roll width12 feet covers most bedrooms without seams.Waste recommendationCovers cutoffs, trimming, and room irregularities.

Waste allowance

Patterned carpet (+10% pattern alignment)

Step 3Stair carpetOptional

Include carpeted stairs in estimate

Step 4Padding and suppliesOptional

Include carpet padding (cushion)Include perimeter tack strips (4 ft sticks)

Doorways with transitions

doors

Count transitions between carpet and other flooring types.Padding roll coverage

sq ft

Standard cushion rolls are 30 sq yd (270 sq ft).

Step 5Cost estimate and quote checkerOptional

Carpet pricing unitCarpet price

Padding price (per sq ft)

Typical 8-lb cushion ranges from $0.50 to $0.90 per sq ft.Installation labor (per sq ft)

Leave empty or 0 for DIY installation.

Old carpet removal and hauling ($0.35 per sq ft)

Guide

How to measure and calculate carpet accurately

Carpet is ordered by the square yard and cut from continuous rolls. Understanding roll width, seams, and pile direction prevents costly ordering mistakes.

How to calculate carpet square yards and roll cuts

Carpet ordering is unique in home improvement because broadloom carpet is produced in fixed roll widths (almost always 12 feet or 15 feet) and sold by the square yard. A simple length-times-width formula often underestimates how much carpet you need because it ignores roll cuts, offcuts, and pile direction.

Carpet order formulasSquare yards = (Total square feet with waste) ÷ 9

Roll cut length = (Number of strips × Room length). One square yard equals 9 square feet. For example, a 12 ft × 15 ft bedroom equals 180 sq ft (20 sq yd). From a 12-foot roll, it requires one 15-foot cut, plus 10% waste buffer (16.5 linear feet = 22 sq yd).

Why roll width and seams dictate your project

When a room width is smaller than or equal to the roll width, installation is seamless. If a bedroom is 11 feet wide and 16 feet long, a 12-foot roll covers it with a single 16-foot cut. The 1-foot offcut along the side is trimmed away.

However, when a room measures 14 feet wide, a 12-foot roll cannot cover it in one pass. The installer must run one 12-foot wide strip and a second 2-foot wide filler strip along the length of the room. Because both pieces must share the same pile direction, that 2-foot strip requires buying an additional cut from the 12-foot roll unless you choose a 15-foot roll instead.

Padding, tack strips, and accessories

Broadloom stretch-in carpet requires three companion components: cushion (padding), perimeter tack strips, and transition bars at doorways. Cushion cushions footsteps, insulates against cold subfloors, and prevents backing delamination. Tack strips grip the stretched backing along the room perimeter, while transition moldings protect cut edges at hard flooring junctions.

When planning a complete flooring renovation, compare broadloom carpet with hard-surface options using our Flooring Calculator or our Vinyl Plank Flooring Calculator. If you have irregular alcoves or odd dimensions, verify room dimensions first with our Square Footage Calculator, and double-check cutting margins using our Waste Allowance Calculator.

According to the Carpet and Rug Institute (CRI 104 standard for commercial carpet and CRI 105 for residential carpet), cushion thickness for standard residential cut-pile carpet must not exceed 7/16 inch with a minimum density of 6 pounds per cubic foot. You can also consult the EPA Indoor Air Quality Flooring Guide to learn about low-VOC materials and CRI Green Label Plus certification.

Estimate carpet in six steps

Measure every room and closetMeasure length and width at the widest points of each room, including doorways, closets, and alcoves.
Select your roll widthChoose standard 12-foot broadloom (most common) or 15-foot wide rolls to minimize seams in larger living areas.
Check roll orientation and seamsDetermine whether room width exceeds the roll width. Orient cuts so all carpet strips run in the exact same pile direction.
Add waste and pattern allowanceAdd 10 percent waste for basic rectangular rooms, 15 percent for rooms with closets and hallways, or 20 percent for patterned carpet.
Convert square feet to square yardsDivide your total square footage (including waste) by 9 to get the square yards needed for retailer quotes.
Calculate cushion and tack stripsOrder matching square footage of 7/16-inch 8-pound cushion, calculate 4-foot perimeter tack strips, and count doorway transitions.

Carpet pile direction (nap)

Carpet fibers have an inherent grain or sweep. Light reflecting across the pile versus against the pile creates different shades. Always keep all strips in a room running in the same direction, and avoid using cross-grain remnants for seams.

Carpet cushion specifications

The Carpet and Rug Institute recommends a cushion thickness between 3/8 inch and 7/16 inch with a density of at least 6 to 8 pounds for residential cut-pile carpet. Pad that is too thick causes carpet backing to flex and buckle over time.

Pattern repeat allowances

Patterned carpets require extra material to match motifs across seams. A 6-inch by 6-inch repeat requires an additional 5 to 10 percent overage, while large 18-inch repeats may require up to 20 percent extra roll length.

FAQ

Frequently Asked Questions

Answers to common questions about carpet yardage, roll sizes, padding, seams, and installation costs.

How do I convert square feet to square yards for carpet?

Divide your total square footage by 9. Because one linear yard equals 3 linear feet, one square yard equals 9 square feet (3 ft × 3 ft). For example, a 180 sq ft bedroom requires 20 sq yd of carpet before waste (180 ÷ 9 = 20). If you add a 10 percent waste factor, you need 198 sq ft, which equals 22 sq yd.

Why does carpet come in 12-foot and 15-foot rolls?

Broadloom carpet is manufactured on continuous industrial tufting looms in fixed roll widths. In North America, 12 feet is the standard residential width, while 15 feet is available for larger open-concept rooms. Some specialty European and woven wool rolls come in 13.5-foot (4.1-meter) widths.

What happens if my room is wider than 12 feet?

If a room is wider than the roll width, the installer must create a seam. For example, a 14 ft × 18 ft room carpeted with a 12-foot roll requires one main 12 ft × 18 ft cut plus a 2 ft × 18 ft filler piece seamed along the wall. Alternatively, ordering a 15-foot roll allows that room to be covered seamlessly with a single cut.

Why is carpet pile direction (nap) so important for seams?

Carpet fibers naturally lean in one direction, known as the nap or pile sweep. When two pieces of carpet meet at a seam, both pieces must run in the exact same pile direction. If one piece is turned 90 degrees or reversed, light reflects differently off the fibers, making the two pieces look like completely different colors even though they were cut from the same roll.

How much waste should I add when ordering carpet?

For a single rectangular room with simple geometry, a 10 percent waste allowance is standard. For multiple rooms, hallways, closets, or rooms with angled walls, plan for 15 percent waste. If you choose a patterned carpet that requires pattern matching across seams, increase your waste allowance to 20 percent.

How much carpet padding do I need, and what thickness is best?

Carpet padding (cushion) should match the net square footage of the room plus 5 percent for trimming. Residential carpet manufacturers and the Carpet and Rug Institute recommend a maximum pad thickness of 7/16 inch with a minimum density of 6 to 8 pounds per cubic foot for standard cut-pile carpet. Thicker padding can cause excessive flexing and void manufacturer warranties.

How do you calculate carpet for stairs?

Each standard stair step requires approximately 1.5 to 2 linear feet of carpet depending on the install style. For a waterfall installation (carpet cascades smoothly over the nose to the tread below), allow 18 inches (1.5 ft) per step. For a Hollywood or cap-and-band installation (carpet is tucked tightly under the nosing), allow 21 inches (1.75 ft) per step. Multiply by the step width (usually 3 feet) to find total stair square footage.

How many tack strips do I need for a carpeted room?

Tack strips are installed along the entire room perimeter, leaving out doorways where transition strips go. Tack strips are sold in 4-foot wooden sticks. To calculate sticks, add the lengths of all walls, subtract doorway openings, and divide by 4. For stairs, add two tack strips per step: one on the tread near the riser, and one on the riser near the bottom.

Can I reuse existing carpet padding or tack strips?

Existing tack strips can be reused if the wood is solid, dry, and all angled pins are sharp and rust-free. However, old carpet padding should almost always be replaced. Over time, cushion breaks down, loses rebound elasticity, traps pet odors, and collects fine dirt that cannot be removed by vacuuming. Installing new carpet over worn pad leads to premature carpet wear and invalidates warranties.

How much does professional carpet installation cost?

Professional installation typically ranges from $0.75 to $1.50 per square foot ($6.75 to $13.50 per square yard) for standard rooms. Additional charges often apply for stairs ($5 to $15 per step), removing and hauling away old carpet ($0.25 to $0.50 per square foot), moving heavy furniture, or leveling uneven subfloors.