How much carpet do you need?

How do I calculate how much carpet I need?

Multiply the length of the room by its width to get square feet, add 10% for seams and trimming, and divide by 9 to get square yards. A 12 by 15 ft room is 180 square feet; with 10% extra that is 198 square feet, or 22 square yards.

How much extra carpet should I order?

About 10% for a simple room no wider than the roll. Carpet usually comes 12 ft wide, so a room 14 ft wide needs a second strip and a seam, and the leftover strip is often wasted — plan on 15 to 20% there, and for patterned carpet that has to line up at the seams.

How do I convert square feet to square yards?

Divide by 9, since a square yard is 3 by 3 feet. 180 square feet is 20 square yards; 198 square feet is 22. Stores quote carpet by the square yard or by the square foot — enter the price in either row to compare.

Do I need carpet pad, and how much?

Yes — pad makes carpet last longer and feel softer, and many warranties require it. You need the same area as the carpet; the calculator lists it under Also for the job.

How do I measure stairs for carpet?

For each step, measure the width and add the depth of the tread to the height of the riser. A 3 ft wide step with a 10 in tread and a 7.5 in riser takes 3 ft × 17.5 in, about 4.4 square feet. Add the stairs as one more area: the width by the tread-plus-riser length times the number of steps.

Why do I need more carpet than the floor area?

Carpet is cut from a roll of fixed width. A room 14 ft wide on a 12 ft roll needs 2 strips, each 16 ft long, which is 2 × 16 × 12 = 384 square feet to buy for a 224 square foot room. The 160 square feet that remain are an offcut, which can sometimes be used in a closet.

How much carpet do stairs take?

For a 12-step staircase of 3 ft wide steps with a 10 inch tread and a 7½ inch riser, each step is 3 ft × 17.5 in = 4.4 square feet, so the stairs take 52.5 square feet or 5.8 square yards, before extra for waste and the pattern.

Which way should the carpet run?

Carpet has a pile direction, and the strips should all run the same way so that the color looks even. The installer plans the seams to fall away from the main walking path and the doorway, so tell the store about the layout when you order.

How the calculation works

The calculator turns each room into square feet, adds the extra you choose for seams and trimming, and divides by 9 to convert to square yards, because a square yard is 3 ft by 3 ft. It lists carpet pad separately, since pad covers the same area as the carpet. The result is the area to buy as a minimum; it does not know the width of your roll. For a room wider than the roll, the roll width and the room dimensions decide how many strips are needed, as in the example below.

Worked example

A room is 16 ft by 14 ft, which is 224 square feet or 24.9 square yards. With the 10% extra from the calculator you would order 246.4 square feet, or 27.4 square yards. On a 12-ft-wide roll the room is 14 ft across, so it takes 2 strips of 16 ft each: 384 square feet, or 42.7 square yards. That is 15.3 square yards more than the simple allowance, which is why a seam layout from the installer matters.

Common mistakes

• Ordering the floor area exactly. Seams, trimming and the width of the roll all add to the amount you need, so a measured area is a lower limit.
• Forgetting the doorways and closets. Add each closet and doorway threshold as its own area, or the carpet will stop short.
• Mixing prices by the foot and by the yard. One square yard is 9 square feet, so a price of $3 per square foot is $27 per square yard.

Sources and related calculators

Method: area arithmetic (1 square yard = 9 square feet); roll width and seam layout depend on the carpet and the installer. Related: square yards calculator, square footage calculator and area calculator.