Carpet Calculator
This carpet calculator turns room length and width into square feet, square yards with waste, padding, and an optional cost. A room wider than the 12 ft or 15 ft roll on both sides includes a seam.
How to use
- Enter each room’s length and width in feet. Add a row for another room. For stairs, use tread depth plus riser height as the length, times the stair width.
- Choose a 12 ft or 15 ft roll. The default is 12 ft.
- Set the waste percent. The default is 10% for trimming, seams, and pattern matching.
- Optionally enter a price per square yard for carpet and for pad. Leave a price blank to skip that cost.
Formula
Room area in square feet = length × width. Square yards = area ÷ 9. Square yards with waste = square yards × (1 + waste ÷ 100). If both sides are wider than the roll, the shorter side is covered with whole roll widths (rounded up) and that purchased area replaces the raw area before the waste percent. Pad square yards are the raw floor area ÷ 9, without pattern-matching waste. Cost adds carpet yards with waste times the carpet price and pad yards times the pad price.
Example. A 12 × 15 ft room is 180 sq ft, or 20 square yards. With 10% waste that is 22 square yards of carpet. Pad stays at 20 square yards. A 12 ft roll covers the 12 ft side, so no extra seam is added.
Example. A 13 × 15 ft room on a 12 ft roll needs a seam. Two roll widths cover the 13 ft side, so the purchase is 24 × 15 = 360 sq ft, or 40 square yards, then 44 square yards at 10% waste. Pad is 195 ÷ 9 = 21.667 square yards.
Frequently asked questions
How do I convert square feet to square yards?
Divide by 9. A 12 x 15 ft room is 180 sq ft, or 20 square yards.
How much extra carpet should I buy?
Plan on roughly 10% extra for seams, pattern matching, and trimming. Odd-shaped rooms may need more.
How wide are carpet rolls?
Most broadloom carpet comes in 12 ft widths, and some styles in 15 ft. Rooms wider than the roll need a seam.
Do I need the same amount of padding?
Usually yes. Pad covers the same area as the carpet, though it has less waste because it does not need pattern matching.
How do I measure stairs?
Measure tread depth plus riser height, times stair width, for each step, then add it to the room total.
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