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Carpet Calculator

Work out how much carpet to order for one or more rooms. The calculator lays each room out on a 12 or 15 ft roll the way an installer would, so the result includes offcuts and seams, then adds padding and the total cost.

Currency

Units

FeetMeters

Carpet roll width

Rooms (length × width, one per line)

Measure wall to wall at the widest point. Add a room name after the numbers if you like. Closets can be added as their own line.

Extra waste allowance

On top of roll offcuts: pattern matching, mistakes. 5-10%.

Prices (optional)

Prices are per

sq ftsq yd

Carpet price

Padding price

Installation price

Charged on the floor area.

Enter your values to see the result.

How to use the Carpet Calculator

Choose feet or meters and the width of the carpet roll you are buying (12 ft is standard in the US).
List your rooms, one per line as length × width, for example 12 x 14 Bedroom.
Set the extra waste for pattern matching or mistakes (5-10%).
Add prices for carpet, padding and installation if you want a cost estimate.
Read the results: carpet to buy, roll length, seams and cost, and check each room in the table.

How carpet is measured

Floor area = length × width for each room. Square yards = square feet ÷ 9.

Roll layout: carpet comes off a roll of fixed width (12 ft is standard in the US, 4 m or 5 m in Europe and elsewhere). For each room the calculator tries both directions: number of strips = ⌈side across the roll ÷ roll width⌉ and cut length = the other side + 3 in trim at each end (6 in total, or 15 cm in metric). Carpet from the roll = strips × roll width × cut length, and the smaller of the two directions is used. Then your extra waste percentage is added.

Example: a 14 × 10 ft room on a 12 ft roll. Running along the 14 ft side, the 10 ft width fits in one strip: 1 × 12 × 14.5 = 174 sq ft (19.3 sq yd) for 140 sq ft of floor. Turning it the other way would need 2 strips: 2 × 12 × 10.5 = 252 sq ft, so the first direction is better.

Real installers also consider pile direction (all pieces must run the same way), where seams fall, and whether offcuts can fill closets, so the calculator is an estimate for ordering and budgeting.

Square feet to square yards for common room sizes

Room	Floor area	Square yards	From a 12 ft roll
10 × 10 ft	100 sq ft	11.1 sq yd	12 × 10.5 = 126 sq ft (14 sq yd)
12 × 12 ft	144 sq ft	16 sq yd	12 × 12.5 = 150 sq ft (16.7 sq yd)
12 × 15 ft	180 sq ft	20 sq yd	12 × 15.5 = 186 sq ft (20.7 sq yd)
11 × 14 ft	154 sq ft	17.1 sq yd	12 × 14.5 = 174 sq ft (19.3 sq yd)
14 × 16 ft	224 sq ft	24.9 sq yd	2 × 12 × 14.5 = 348 sq ft (38.7 sq yd)
20 × 12 ft	240 sq ft	26.7 sq yd	12 × 20.5 = 246 sq ft (27.3 sq yd)

Rooms just over 12 ft wide waste the most carpet on a 12 ft roll: consider a 15 ft roll or using the offcut strip in a closet or hallway.

Frequently asked questions

How do I calculate how much carpet I need?

Multiply each room's length by its width to get square feet, then plan how the room is cut from the roll. Carpet comes in 12 ft (sometimes 15 ft) wide rolls, so a 14 × 16 ft room needs two strips or a 15 ft roll. Add a few inches of trim at each end and 5-10% for waste.

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

Divide square feet by 9, because one square yard is 3 ft × 3 ft = 9 sq ft. For example 180 sq ft ÷ 9 = 20 sq yd.

Why do I need more carpet than my floor area?

Carpet is cut from a fixed-width roll. A 10 ft wide room cut from a 12 ft roll wastes a 2 ft strip, and rooms wider than the roll need extra strips joined with seams. Installers also add about 3 inches at each end of every cut for trimming.

Should I use a 12 ft or 15 ft carpet roll?

Use 12 ft for most rooms up to 12 ft wide. A 15 ft roll avoids a seam in rooms 12 to 15 ft wide, but it is less common and wastes more in narrow rooms. Compare both in the calculator.

How much padding do I need under carpet?

Padding (underlay) is cut to the room and does not need to match the carpet direction, so you need about the floor area plus a small waste allowance. Seams in padding are not visible.

How much waste should I add for carpet?

With the roll layout already included, add about 5% for trimming errors. Use 10% or more for patterned carpet that must be matched at seams, stairs, or rooms with many angles.

Does this include stairs?

No. Stairs are measured per step: for each stair, add the tread depth and riser height plus about 2 inches, multiply by the stair width, and add the stairs as extra lines (for example 13 stairs at 3.5 × 1 ft).

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