How to Measure for Carpet

Two little girls laying on carpet floor

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You will need to know how to measure a room for carpet in order to get a realistic idea of how much is required. It is one of the first steps before shopping for carpet to install yourself or providing installers with the needed dimensions. Making measurements most often applies to broadloom wall-to-wall carpet. Measuring a basic square or oblong area is easy, so long as you make allowances for doorways and entry stairs.

Measuring for Carpet

Gather a measuring tape or a laser distance measurer, a calculator or calculator app, paper and writing instruments or a note-taking app, and graph paper and a pencil, if you choose to draw your layout.

Most measuring tasks are easier done with two people if you are using a measuring tape. You can do it solo if you are using a laser distance measurer.

Measure Room Width and Length

  1. Lay your tape measure against the wall at one end of your room, and then extend it to the opposite wall. Or, use a laser distance measurer to find the measurement between the two walls. Note this number as the length.
  2. Do the same for the other two walls in the opposite direction. Note this number as the width.

If your room is L-shaped, measure it as two separate rooms. Measure the long portion of the L as one room and the short portion of the L as another room.

Closets should be measured as their own separate rooms.

Measure to the Middle of Doorways

Unless your room is entered by a step, all rooms have a doorway leading into them. Some rooms have additional doorways to closets and bathrooms. You must be sure to measure into the middle of the doorway. This will add 2 to 3 inches to your overall measurement. If you have a doorway at either end of the room, you may need to add up to 6 inches to the total room dimension.

  1. For each wall that has a doorway (including closet doors), measure to the middle of the door frame. Use the highest number of inches found for any one wall, and use only one number per wall.
  2. For each wall, add the number of doorway-allowance inches to width or length, as appropriate.

Example: One wall has an entry door and a closet door. Measuring to the middle of each gives a result of 2 inches for the entry door and 1.5 inches for the closet door. The opposite wall has no doors. Add 2 inches to the wall-to-wall measurement.

Example: One wall has an entry door and the opposite wall has a door into the bathroom. Measuring to the middle doorway you find 2 inches for each. Because these are on opposite walls, you need to add both to the wall-to-wall measurement, so add 4 inches.

Measure Carpet for Stairs

When measuring an area that leads to stairs going down (such as a hallway or landing), be sure to measure around the nosing (the ledge at the top of the stairs). Hold your tape measure against the opposite wall (or halfway into a doorway), and wrap it all the way around the nosing until it touches the back (riser) of the stair below. Your carpet will need to be this measurement in order to wrap around the nosing.

Measuring for the stairs themselves involves special considerations such as the shape, size, and configuration of the stairs, as well as the direction of the pile and pattern motifs (if applicable).

Calculating Square Footage

You now have the measurements needed, with allowances for doorways and appropriate measurements for stairs included, to calculate the square footage of the room. Multiply the width of the room by the length of the room. Note this total.

Add a Little Extra

Once you have taken your measurements, you should always add a little extra to your requirements. This allows for walls that are not perfectly straight and gives you a bit of a safety net. When measuring, add about 3 inches to each piece of carpet you will need.

Square Feet vs. Square Yards

Although most of the floor covering industry has transitioned to the standard unit of square feet, some retailers and installers still prefer to use the square yard.

There are 9 square feet in 1 square yard; to convert square feet into square yards, divide your total by 9.

For example, 12 feet by 10 feet is 120 square feet, which is 13.33 square yards (120 divided by 9).

Carpet Widths

Unfortunately, just calculating the square footage of your room won't tell you how much carpet you will have to buy. Broadloom comes in specific widths—usually 12 feet or 15 feet, but sometimes 13 feet 6 inches. Therefore, when you buy a piece of carpet off the roll, you have to buy the length you need, by the width of the roll.

For example, if your room is 10 feet by 10 feet—which equals 100 square feet—and you are buying a carpet that comes in a 12-foot width, you will actually need to buy 12 feet by 10 feet of carpet, which equals 120 square feet.

If you are carpeting a fairly small area, you may be able to find a carpet remnant that will save you from having to purchase extra carpet.

Once you've mastered the basics of measuring, the next step is to figure out how much carpet you will need. Understanding pile direction and its effect on your measurements will help you to calculate your carpet requirements.

When to Call a Professional

The math gets much more difficult if your room layout has slanting or curved sides. As well, you might have an island, stove, or fireplace hearth you will need to carpet around. For these challenges, it may be best to have the room measured by a professional.