How to Use a Carpenter Square

A carpenter square is a common tool that builders use to help lay out a variety of elements of wood construction jobs including rafters, roofing and staircases. Also called a framing square, rafter square or a steel square, it is one of the most versatile tools a carpenter uses. It enables him or her to measure, define angles and lay out the edges and details of a square. A carpenter square is L-shaped with measuring increments on it, and is typically made of some type of metal, such as aluminum or stainless steel. If you are a carpenter, builder or home project enthusiast, learning how to use a carpenter square will save time and help you to get precise measurements for projects that involve angles and squares.


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    Gather a carpenter square and your materials for your building project.
    • Building stairs or roof rafters are common projects which include measuring angles with a carpenter square.
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    Figure the approximate height and distance of your project.
    • For example, the number of stairs and length of each step, or the pitch of your roof.
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    Measure the layout of the steps, or roof rafters, with your carpenter square.
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    Mark the measurements laid out with your carpenter square on the wood with a pencil.
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    Repeat each measurement with the carpenter square for each step.
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    Follow the proper distance and repeat the measurements for each rafter from the pitch of your roof if laying out rafters with your carpenter square.
    • Use your carpenter square to measure other elements of your construction job.
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    Keep your carpenter square with you as you progress with your roof rafters or stairs in case you need to make a quick measurement.
    • In a pinch, a carpenter square can be used to measure elements other than angles.


  • Once you know how to use a carpenter square, you can use it for a variety of construction measurements and projects. A carpenter square will come in handy for any wood construction project that involves repeat angles and squares.
  • The measuring increments on a carpenter square are called the rafting table. The numbers are broken down according to roof pitches. Measuring roof rafters is the most common use of carpenter squares.
  • When learning how to use a carpenter square, it is important to have knowledge of roofing or building. If not, the measurements can be confusing to a novice builder.
  • When purchasing a carpenter square, it is best to invest in one that is high quality. A carpenter square made of stainless steel is the best, most durable choice. If you purchase a carpenter square of less quality, keep in mind that it might be damaged during a construction job.


  • Do not use a carpenter square for roofing until you have basic knowledge of how to use it. If not, you could end up with an uneven roof.
  • Do not hesitate to ask the staff at a hardware or home improvement store if you have any questions about using a carpenter square. This will help you prevent measuring mistakes in your construction project.

Things You'll Need

  • Building materials
  • Framing square
  • Pencil

Article Info

Categories: Tools