How much carpet do I need for a room?

Multiply the room's length by its width, then add a waste allowance of 5–10% (more for patterned carpet). A 12 × 15 ft room is 180 sq ft, so plan on roughly 190–200 sq ft of carpet.

Why do I need a waste factor?

Carpet comes in fixed-width rolls (typically 12 ft), so cuts rarely match the room exactly, and seams, closets, doorways, and pattern matching all consume extra material. Skipping the allowance is the most common reason installations come up short.

How do I convert square feet to square yards?

Divide by 9, since a square yard is 3 ft × 3 ft. Carpet in the US is often priced per square yard, so a 180 sq ft room needs 20 sq yd before waste.

Do I need new padding too?

Usually yes — pad the same area as the carpet. Quality padding extends carpet life, improves comfort and sound, and is cheap relative to the carpet itself; reusing old, compressed pad can void carpet warranties.

How do I measure an irregular room?

Split the floor plan into rectangles, calculate each area, and add them up. Measure at the longest and widest points of each section, and include closets and doorway transitions where the carpet will continue.

Carpet Calculator

Estimate carpet needed for a room in square yards or meters, plus padding and waste allowance. Get instant cost estimate

Room Dimensions

Units

Length (feet)

Width (feet)

Room Area

120.0 sq ft

Total floor space

Material Costs

Carpet Price per Sq Ft

Padding Price per Sq Ft

Installation Labor per Sq Ft

Waste Factor (%)

Project Summary

Total Project Cost

$840.00

$7.00 per sq ft

Total Area

120.0 sq ft

Actual coverage needed

With Waste

132.0 sq ft

+10% waste factor

Cost Breakdown

Carpet Material

132.0 sq ft × $3.5

$462.00

Carpet Padding

132.0 sq ft × $0.75

$99.00

Installation Labor

132.0 sq ft × $2

$264.00

Transition Strips

1 strips × $15

$15.00

Money-Saving Tips

• Buy carpet and padding together for bundle discountsSave $84.00

• Schedule installation during off-peak seasons (winter)Save $39.60

• Remove old carpet yourself to save on removal feesSave $60.00

• Purchase from wholesale/warehouse storesSave $92.40

How it works

A carpet calculator finds the area to cover, often in square yards since carpet is sold that way. Compute the room area in square feet and divide by 9 to get square yards, then add waste for seams and cuts.

Carpet area

Square feet = length × width        Square yards = ft² ÷ 9

length, width: room dimensions in feet
÷ 9: square feet per square yard

Worked example

Room 12 ft × 15 ft

Area = 12 × 15 = 180 ft²
Square yards = 180 ÷ 9

20 square yards — add ~10% for seams and waste.

Good to know

Carpet comes in fixed roll widths (often 12 ft), so the cut may waste more than the bare area suggests.
Plan seam placement away from high-traffic and high-light areas.
Don't forget padding/underlay and tack strips.