Flooring & Finishes

Carpet Calculator

Enter your room dimensions to find how much carpet to buy in square feet and square yards, with an allowance for seams and trimming.

Updated Oct 2, 2026A free tool from homesblogs

What is a carpet calculator?

This calculator gives the area of carpet you need for a rectangular room, converted to square yards — the unit many carpet retailers still quote — with a waste allowance for seams and edge trimming.

How does it work?

Length × width gives the room area. The waste percentage is added, then the total is divided by 9 for square yards. It also estimates how many linear feet you would cut from a standard 12 ft roll. For hard flooring in the same room, try the Flooring Calculator.

What information is needed?

  • Room length and width in feet
  • Waste allowance
  • Price per square foot (optional)

How to use the Carpet Calculator

  1. Measure the longest and widest points of the room, including closets.
  2. Enter a waste allowance — 10% for most rooms.
  3. Add the price if you have a quote.
  4. Select Calculate.

The formula

In plain terms, here is the calculation the tool runs:

Area = L × W
Carpet = Area × (1 + Waste ÷ 100)
Square yards = Carpet ÷ 9
L, W
Room length and width in feet
9
Square feet in one square yard

Worked example

Example

A 14 × 12 ft bedroom with 10% waste at $3.25 per sq ft installed.

  1. 14 × 12 = 168 sq ft
  2. 168 × 1.10 = 184.8 sq ft
  3. 184.8 ÷ 9 = 20.5 sq yd
  4. 184.8 × $3.25 = $600.60

Buy about 185 sq ft (20.5 sq yd), roughly $601 installed.

Frequently asked questions

Why does my quote show more carpet than the room area?

Carpet comes off a 12 ft or 15 ft roll, so a 13 ft wide room uses two widths or a cross-seam. Installers quote the carpet actually cut, not just the floor area.

Is pad measured the same way?

Yes, but pad has less waste because it can be pieced without visible seams.

Should carpet run under the door?

Carpet usually stops under the door, centred, at a transition strip.

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