How to calculate how much carpet you need for a room

When purchasing carpet, salespeople will typically measure your room and tell you exactly how much you need. Still, it is always a good idea to know in advance how much you will need to do your room. First, you do not want any surprises when the salesperson prices out your carpet. Secondly, you want to know that the salesperson is calculating your carpet correctly and that you won't end up with too much or too little. Here are the steps on how to calculate how much carpet you need for a room.

Measure the room and draw the room layout. Measure the room by length and width using a retractable measuring tape or laser tool. Transfer the measurements to paper. Be sure to accurately draw any distinct features of the room such as bay windows or angled walls.

Choose your carpet and purchase the correct width carpet for the room. Carpet comes in three basic widths, 12 feet, 13-6 and 15 feet. The majority of carpets come in 12 feet. If you have a room that is wider that 12 feet you may want to purchase a 15-foot wide carpet.

Draw the layout of the carpet on the room layout. The key to drawing the layout of the carpet is to avoid having too many seams in the room. If you do need to have a seam in the room, you want to avoid having it in a traffic pattern or down the centre of the room. In this illustration, the 12-foot wide carpet is wider than the 10-foot room so the layout will be easy.

Determine the needed length of the carpet (linear footage) you need to purchase. After you have drawn your carpet layout, you need to look at the drawing and determine how many linear feet you need to purchase according to the plan. In this case, the 15-foot carpet is 3 feet too small for the room's width. Therefore, you will need a second length of carpet to piece into the remaining area.

Calculate your carpet price based on square yard price. Calculate price based on the amount of carpet you need to purchase plus a 10 per cent allowance for waste. Since carpet is priced by square yard, you need to convert the square foot amount into square yards. To obtain square feet multiply the length by the width of the carpet. Next, convert square feet to sq. yards by dividing the square foot amount by 9. Multiply this amount by the square yard price to estimate the price of your carpet.


If your carpet salesperson's numbers are substantially off from yours, have them show you the layout and explain why it is different. It could be because of seam placement in a low traffic area, or available carpet width.

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Things Needed

  • Measuring tape
  • graph paper
  • Ruler

About the Author

Andrea Hermitt is an artist and writer who loves to research and write about new things. She's been a content writer since 2000, contributing to, the blog Notes From A Homeschooling Mom and other online publications. Hermitt has a Bachelor of Arts in fine art and English from the State University of New York at Albany.

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