The Build Calculator

Carpet Calculator

Calculate carpet in square feet and square yards from your room size — with roll-width waste, padding, and a full installed-cost estimate.

Carpet needed (incl. waste)
sq yards
sq ft to buy
actual floor area
linear ft of 12 ft roll

Enter a price per sq yd to estimate cost.

You might also need:Flooring Calculator·Tile Calculator

Carpet math

sq ft to buy = (room area + closets) × waste factor
square yards = square feet ÷ 9

A 16 × 12 ft bedroom is 192 sq ft — 211 with 10% waste, or 23.5 square yards. Because carpet comes on 12 ft rolls, a 12 ft room width is ideal; a 13 ft width forces either a seam or a wasteful 15 ft roll, which is exactly why measuring before shopping saves real money.

Square feet to square yards

Room sizeSquare feetSquare yards (+10%)
10 × 10 ft10012.2
12 × 12 ft14417.6
12 × 15 ft18022.0
16 × 12 ft19223.5
20 × 15 ft30036.7

Ordering tips

  • Mind the roll width: 12 ft is standard. Rooms wider than 12 ft need a seam — place it out of the main sightline and away from doorways.
  • Carpet has a nap direction: all pieces must run the same way or the color looks different between them under light.
  • Replace the padding with the carpet — reusing old padding is the fastest way to make new carpet feel old.
  • Hard flooring instead? The flooring calculator covers laminate, vinyl and hardwood, and tile handles per-tile counts.

Frequently asked questions

How do I calculate how much carpet I need?+

Measure the room in feet, multiply length by width for square feet, then divide by 9 for square yards — carpet is usually priced per square yard. Then add waste for the roll width: carpet comes in 12 ft (sometimes 15 ft) rolls, and any room dimension that is not a neat fit creates offcuts.

How many square feet are in a square yard of carpet?+

Nine. A square yard is 3 × 3 feet. Retailers quote both — always check which unit a price refers to, because a "$3 carpet" is very different at $3/sq ft versus $3/sq yd.

How much extra carpet should I order?+

Add 10% for a simple rectangular room and up to 20% for rooms with closets, alcoves or where the width forces awkward seaming. Patterned carpet needs more again for pattern matching — sometimes an extra repeat length per seam.

Do I need new carpet padding?+

Almost always — padding compresses over time and old padding will shorten the life of new carpet, often voiding the warranty. Standard residential padding is 7/16 inch thick at 6–8 lb density; thicker is not automatically better, and over-thick padding can damage carpet backing.

How much does carpet installation cost?+

Carpet itself runs $2–$7 per square foot; padding adds $0.30–$0.75. Installation is typically $0.50–$1.50 per square foot, plus removal and disposal of the old carpet at $0.25–$0.50. Many retailers bundle install into promotional pricing.

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