How to Measure for Carpet

Make sure you know how to properly measure for carpet with these simple steps

Person measuring a room for carpet

The Spruce / Sanja Kostic

Project Overview
  • Working Time: 15 - 45 mins
  • Total Time: 30 mins - 1 hr
  • Skill Level: Beginner
  • Estimated Cost: $0

Installing new carpet or replacing old carpet to give your home an updated look is a great renovation project, but before you can start rolling out the carpet and tacking it down, you need to measure the space to ensure that you get enough carpet to complete the job. Basic square or rectangular rooms are relatively easy to take length and width measurements, then calculate the square footage to find the approximate amount of carpet you need for the room.

However, homes are not only made up of rectangular and square rooms. You also need to take into consideration triangular corners, rounded edges, door ways, L-shaped layouts, and any interior spaces, like closets. Follow the straightforward steps in this guide to learn how to measure for carpet.


If you're not installing the carpet yourself it's recommended to have the installer come out and measure for accuracy.

Before You Begin

To ensure that you don't mix up your measurements, it's highly recommended to grab a piece of paper and a pencil, then sketch out the layout of the home. If you are only measuring for carpet on one floor, then just sketch that floor of the home. Make sure to include any interior spaces, like closets or pantries.

The sketch doesn't need to be 100 percent accurate as long as it roughly matches the layout and proportions of the home. Take this opportunity to separate odd-shaped rooms into easy-to-measure parts. For instance, you can split an L-shaped room into two parts, take length and width measurements of each part, then add the square footage of the two parts to find the total square footage for the room.

What You'll Need

Equipment / Tools

  • Tape measure
  • Calculator


  • Pencil
  • Paper


Materials needed to measure for carpet

The Spruce / Sanja Kostic

  1. Measure the Length and Width of the Room

    If you are measuring multiple rooms, decide which side of your home is the length and which is the width. This will help to keep your measurements neatly organized and easy to understand.

    With your sketch of the home's layout nearby, use a measuring tape to measure the length and width of the room where you will be installing carpet. Write down the measurements for future reference.

    Make sure that if there is a doorway on one wall, you measure to the center of the doorway instead of the wall to account for the extra two to three inches.

    Measuring the length and width of a room with measuring tape

    The Spruce / Sanja Kostic

  2. Measure Interior Spaces Individually

    Any interior spaces, like a closet or pantry, should be measured independently of the rest of the room. Open the closet door and take length and width measurements, remembering to measure to the center of the doorway, instead of to the wall to account for the additional two to three inches.

    If you are measuring to an area with stairs leading down, it's important to measure around the nosing on the ledge at the top of the stairs. Wrap the tape measure all the way around the nosing until it touches the back of the riser of the stair below.

    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).

    Measuring the stairs for carpet separately

    The Spruce / Sanja Kostic

  3. Make Split Measurements for Oddly Shaped Rooms

    Not every room is going to be rectangular or square, so you will need to split up oddly shaped rooms into easy-to-measure and label parts. A common example is breaking L-shaped rooms into two separate parts, then measuring the length and width of each part. Even if you have a triangular corner of the room, you can still measure and record the maximum length and width of the space.

    You can also measure the radius of curved walls by recording the distance across the front of the wall, making a straight line from one side of the wall to the other. You will also need to measure the depth of the wall from the top of the curved arc to the front edge of the straight line.

    Breaking up oddly-shaped areas into parts

    The Spruce / Sanja Kostic

  4. Calculate the Area

    To calculate the area of a room or part of a room, there are several calculations you can use based on the measurements you took in steps one through three.

    The first equation is relatively simple. On its own, it can be used for square or rectangular spaces.

    Length x Width = Area.

    If you are dealing with a triangular space, you will need a slightly more complex equation to account for the shape.

    (Length x Width) / 2 = Area

    To find the area of a curved or rounded portion of the room, you need to first find the radius of the curve, then use this information to find the area. Due to the complexity of the equation, it is listed in several detailed steps below.

    1. Divide the curve depth by 2.
    2. Square the curve width.
    3. Multiply the curve depth by 8.
    4. Divide the result from step two by the result from step three.
    5. Add the result from step one to the result from step four to find the radius.
    6. Square the radius.
    7. Multiply the result from step six by π (3.14).
    8. Divide the result from step seven by 2 to find the area.
    Calculating the area of the rooms

    The Spruce / Sanja Kostic

  5. Add Up the Total Square Footage

    For simple square or rectangular rooms, you don't need to add any numbers together. Simply use the area of the room as a reference for your square footage.

    However, if the room is oddly shaped, or it has any interior spaces, then you will need to add the area of each part of the room to find the total square footage. For instance, if the room is L-shaped, then you add the area of the two parts together to get the total square footage.

    After finding the total square footage, it's recommended to multiply the total by 0.1 to add an extra 10 percent to the total. This overage is just a fail-safe to ensure you purchase enough carpet to get the job done.

    Calculating the total square footage

    The Spruce / Sanja Kostic