Carpet Calculator

Calculate carpet needed for a room, accounting for roll width and seam placement. Enter room dimensions and roll width to get exact carpet strips, linear feet, and square yards.

ft

Length of the room (direction carpet will run).

ft

Width of the room (across the carpet roll).

ft

Standard: 12 ft residential, 15 ft commercial. Check with your supplier.

%

Extra for seaming, cuts, pattern matching. Default 10%.

How this calculator works

Carpet is sold by the square yard but installed from rolls of fixed width (12 ft or 15 ft). This calculator accounts for that:

  1. Strips needed: ceil(room width / roll width). When room width exceeds the roll, multiple strips are seamed together.
  2. Carpet length: strips × room length (each strip runs the full length of the room).
  3. Carpet area: carpet length × roll width (includes excess from roll-width overage).
  4. Square yards: carpet area / 9 (carpet pricing unit).
  5. With waste: adds the waste allowance for cuts, pattern matching, and seaming.

The "excess from roll width" is carpet you pay for but cannot use due to the fixed roll width — this is the key difference from the general Flooring Calculator.

Formula

strips          = ceil(room_width / roll_width)
carpet_length   = strips × room_length
carpet_area     = carpet_length × roll_width
carpet_sq_yd    = carpet_area / 9
excess          = carpet_area - room_area
carpet_with_waste = carpet_area × (1 + waste_pct / 100)
sq_yd_with_waste  = carpet_with_waste / 9

Example

For a 15 × 14 ft room with 12 ft roll width and 10% waste:

  • strips = ceil(14 / 12) = 2 strips
  • carpet_length = 2 × 15 = 30 linear ft
  • carpet_area = 30 × 12 = 360 sq ft
  • carpet_sq_yd = 360 / 9 = 40 sq yd
  • excess = 360 - 210 = 150 sq ft (roll-width overage)
  • with waste = 40 × 1.10 = 44 sq yd to order

Important assumptions

  • Standard residential carpet roll width: 12 ft. Commercial: 15 ft. Check with your supplier.
  • Carpet runs along the room LENGTH direction. If your room is wider than the roll, multiple strips are seamed together.
  • "Excess from roll width" is carpet you pay for but cannot use — this is unavoidable waste from fixed roll width.
  • For patterned carpet, increase waste to 15% for pattern matching across seams.
  • This calculator is for carpet specifically. For hard flooring, use the Flooring Calculator.

FAQ

How much carpet do I need for a 12×12 room?
With a 12 ft roll, 12×12 room needs 1 strip × 12 ft = 12 linear ft × 12 ft wide = 144 sq ft = 16 sq yd. With 10% waste: 17.6 sq yd → order 18 sq yd.
What is a carpet roll width?
Carpet comes in rolls of fixed width — typically 12 ft for residential or 15 ft for commercial. When a room is wider than the roll, multiple strips are seamed together, creating waste from the overlap.
Why does the carpet calculator show more material than the flooring calculator?
Carpet must be cut from a fixed-width roll. If your room is 14 ft wide and the roll is 12 ft, you need 2 strips (24 ft total width) — wasting 10 ft of carpet width. The Flooring Calculator doesn't account for this; the Carpet Calculator does.
How is carpet priced?
Carpet is priced per square yard (1 sq yd = 9 sq ft). To convert sq ft to sq yd, divide by 9. Installation, padding, and tack strip are typically priced separately.
Should I order extra carpet for pattern matching?
Yes — patterned carpet needs 15% waste (vs 10% for solid) to match patterns across seams. The waste allowance field lets you adjust this.