Carpet calculator

How to use the carpet calculator

This carpet calculator estimates how much broadloom carpet to buy for a rectangular room and can estimate padding. Enter room dimensions, select a 12- or 15-foot roll, and set a waste allowance to see linear feet, square yards, strips, and seams.

1. Select Feet / inches or Metres / cm.
2. Enter the room Length and Width. Add minor measurements in the plus inches fields if needed.
3. Choose a 12 ft or 15 ft roll width.
4. Set Waste % and choose whether to Include padding.
5. Optionally enter Price per square yard (optional), then review the carpet and padding results.

What to enter

Unit system

Choose Feet / inches for the default US inputs or Metres / cm for metric room dimensions. Imperial is the default.

Length

Room length. The default is 15 ft in imperial mode or 15 m in metric mode. The value must be positive.

plus inches

Add inches to Length in imperial mode or centimetres in metric mode. The default is 0.

Width

Room width. The default is 12 ft in imperial mode or 12 m in metric mode. The value must be positive.

plus inches

Add inches to Width in imperial mode or centimetres in metric mode. The default is 0.

Or a known area

The shared room-size layout includes this label, but the carpet calculation code uses Length and Width only. Enter both dimensions for a reliable carpet result.

Roll width

Choose 12 ft or 15 ft. The default is 12 ft. These roll-width choices remain in feet when metric room dimensions are selected.

Waste %

Extra material for cuts and fitting. The default is 10%. The allowed range is 0% to 50%.

Include padding

Estimate carpet padding area as well as carpet. This is enabled by default.

Price per square yard (optional)

Enter a non-negative material or installed price per square yard to calculate optional carpet cost. It is blank by default.

Default 15 ft by 12 ft room

Use the default imperial inputs: Length 15 ft, Width 12 ft, 12 ft roll width, 10% waste, and padding included. For strips running along the room length, width ÷ roll width = 12 ÷ 12 = 1 strip, and 1 × 15 = 15 linear ft. For strips running along the room width, length ÷ roll width = 15 ÷ 12 = 1.25, which rounds up to 2 strips, and 2 × 12 = 24 linear ft. The calculator chooses along-length because 15 linear ft is less than 24 linear ft. The waste factor is 1 + 10 ÷ 100 = 1.1. Carpet length is 15 × 1.1 = 16.5 linear ft. Carpet purchased is 16.5 × 12 = 198 sq ft, and 198 ÷ 9 = 22 sq yd. Room area is 15 × 12 = 180 sq ft. Cut-off waste is 198 - 180 = 18 sq ft. Padding is 180 × 1.1 = 198 sq ft. Results are 22 sq yd of carpet, 16.5 linear ft off the roll, 1 strip, 0 seams, and 198 sq ft of padding.

How the carpet estimate is calculated

The calculator converts imperial dimensions to decimal feet with Length + plus inches ÷ 12. In metric mode, it converts metres and centimetres to internal feet. It tests two strip directions. Along-length uses ceil(Width ÷ roll width) strips, with linear footage equal to strips × Length. Along-width uses ceil(Length ÷ roll width) strips, with linear footage equal to strips × Width. The smaller linear-foot total wins; a tie goes to along-length. The waste factor is 1 + Waste % ÷ 100. Carpet linear footage is the selected plan multiplied by that factor. Carpet area is linear footage × roll width, and square yards are carpet area ÷ 9. Padding, when enabled, is room area × the same waste factor. The engine rounds numeric result values to two decimal places. Optional carpet cost is calculated as square yards × the entered price per square yard, then rounded to two decimals.

Reading the results

Carpet to buy is shown in square yards. Linear feet off the roll includes the waste allowance. The result also shows the room area, selected strip orientation, number of strips, seam count, carpet purchased area, and cut-off waste. Padding is shown only when Include padding is enabled. Optional carpet cost uses the carpet quantity and does not add a padding price.

Limitations and common mistakes

• The calculation uses Length × Width, so it models a rectangular room. It does not draw an irregular layout or account for separate halls and stairs.
• Only 12 ft and 15 ft roll widths are available. The calculator chooses the direction with the least linear footage, but it does not model pattern repeats.
• The waste allowance applies to linear carpet footage and padding area. Patterned carpet, stairs, and halls may need a different allowance than the default.
• The calculator does not add pattern-repeat allowance and does not calculate padding cost. In metric mode, carpet to buy is still reported in square yards and roll width remains in feet.

Frequently asked questions