Best Double Square

The double square is one of the must-have woodworking and carpentry tools. Just like the speed square, try square, framing square, T square, and combination square, the double square works hand-in-glove to make your jobs such as squareness checking, marking, layout, and scribing become easier.

Professionals should have them all because when it comes down to it, each of them plays a unique role that makes them quite irreplaceable.

The body of a double square consists of a head (handle) and a blade. The head can slide along the blade. Therefore, two things set this tool apart from other woodworking and machinist tools: firstly, they are adjustable, and secondly, they can be applied to check the squareness of corners from both ends. Speed square and try square is not adjustable.

With the double square, you can set repetitive distances on one end and continue checking squareness, measuring, and marking on the other end. From experience, this has been observed to make work quite fast. The double square is also lighter and more portable than most of the other square tools. You can move around easily with them and even temporarily store them in your pocket.

double square
Double square with sliding ruler

If you don’t own one, you are missing a great deal and should get one now. While we are on that, below is the list of the best double squares we have compiled for you. Feel free to purchase the best for your project.

Top 9 Best Double Square Reviews in 2024

1. Starrett 13C [Best Overall]Starrett 13C Double Square - Best OverallBlade: 6"Price!
2. iGaging 34-4466-S [Best Budget]iGaging 4 in & 6 in Double Square Set 4R Steel Blade High Precision Woodworking - Best Budget ChoiceBlade: 4" & 6"Price!
3. Starrett 13AStarrett 13A Double SquareBlade: 4"Price!
4. iGaging 34-244-SiGaging 4 in Precision Double SquareBlade: 4"Price!
5. PEC 7105-406PEC 7105-406 6 in 4R Double SquareBlade: 6"Price!
6. Products Engineering 7104-404PEC 7104-404 Double Square 4 inchesBlade: 4"Price!
7. Fowler 52-435-006-0Fowler 52-435-006-0 Double Square Cast Head with 6 inches BladeBlade: 6"Price!
8. Starrett 13MCStarrett Reading Double Square with Hardened Blades, Millimeter Reading - 150mm Blade Length - 13MCBlade: 150 mmPrice!
9. Starrett 13MAStarrett 13MA Double Square 100 mm for Smaller Metric ProjectsBlade: 100 mmPrice!

1. Starrett 13C Double Square 6″ + Level Vial on the Blade [Best Overall]

Starrett 13C Double Square - Best Overall

As a machinist, toolmaker, or patternmaker, the Starrett 13C is the best double square tool of choice. When you need to check the squareness of an edge of your workpiece, this is the right tool for you. Even, at the same time, you are checking the levelness of the surface where your workpiece lies on.

Since this 6-inch Starrett 13C double square is produced in the United States, you can expect its accuracy and quality. It’s a tough and durable instrument that can withstand a lot of use.

This tool’s head is composed of heavy cast iron and has a black finish. The blade, on the other hand, is constructed of tempered steel and with a general finish.

Starrett 13C double square lets you measure in inches because it comes in the imperial unit graduation. It also has a 3 ½-inch long head and a 9/16-inch broad face. It includes many scales that are useful in woodworking and carpentry. Both sides have graduation scale. The 1/8″ and 1/16″ graduation is on one side, while the 1/32″ and 1/64″ graduation is on the second side.

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  • It is not very hefty.
  • It features useful scales.
  • It’s been machined and polished nicely.
  • It’s constructed of tough, long-lasting material.


  • Its cast-iron head is prone to rust.

2. Igaging 34-4466-S Double Square 4″ & 6″ [Best Budget Choice]

iGaging 4 in & 6 in Double Square Set 4R Steel Blade High Precision Woodworking - Best Budget Choice

This iGaging 34-4466-S double square is for you if you need a tool to verify the outside and inner square with lower cost. The iGaging double square is a 2-in-1 double square that includes both 4-inch and 6-inch squares. This boosts the tool’s adaptability, allowing you to use the appropriate double square for any project, regardless of scale.

This double square’s blade is heavy-duty and is finished with satin chrome. Because it has a hardened steel blade, you can be confident that it will endure a long time and will not wear out due to repeated usage.

On this iGaging double square, the graduations are very visible due to the etched markings. It also has excellent black-on-silver contrast, which aids this hand tool’s readability and visibility.

The 4R (1/8″, 1/16″, 1/32″, and 1/64″) scales are available on this instrument for measuring distances. Nicely, the larger 6″ blade model includes a spirit level which is a nice feature to check the levelness of the object you are checking. It also comes with a case for storing and transporting the tool.

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  • Comes in two units with different lengths (economical choice)
  • A case is for easy storage and keeps the tool organized
  • Comes with a built-in spirit level which is a nice feature


  • There are problems with quality control

3. Starrett 13A Double Square 4″ [Best for Precision]

Starrett 13A Double Square

This Starrett 13A is the best choice for you if you need a portable 4-inch double square that is accurate.

The graduations on this 4-inch double square are in inches since it uses imperial units. The Starrett 13A comes with four scales, including 1/8, 1/16, 1/32, and 1/64, just as many other double squares. The hardened steel blade is extremely robust and wear-resistant.

The precision and ease of use of this Starrett are its main selling points. Because of this tool’s incredible squareness, you can be certain that it is of the highest quality and that your work will always be 90 degrees.

After you tighten the locking nut on some other tools on the market, the blade may not properly lock. It is not the case with the Starrett 13A tool, which is perfectly accurate. Furthermore, unlike some others, the locking thread of this double square loosens and tightens effortlessly.

The tool may be on the pricey side, but you will understand why once you have one and it accurately gauges measurement.

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This is the video comparison between Starrett 13A vs iGaging 34-4466-S by Build It Make It.


  • It’s constructed of long-lasting material
  • The head is easy to slide
  • Can be your depth gauge because the blade width is smaller
  • Graduations are easy to read due to etched
  • The black-on-silver contrast of the graduations is excellent.


  • It’s on the pricey side.
  • No hard case

4. iGaging 34-244-S Double Square 4″ [Best for Beginners]

iGaging 4 in Precision Double Square

In the case of the world of carpentry and need a tool to verify that corners are at a right angle, then the iGaging 4-inch double square is the instrument for you. This excellent iGaging double square is also ideal for machine setup, correct angle marking, and precision measurement. It may easily be tucked into your apron and taken around.

This tool’s head is made from cast iron, while the blade is constructed of hardened steel hence it is strong and resistant to wear and tear. This double square features legible graduation and a nice black-on-silver contrast that enhances its visibility. It has a pleasing look that has been carefully finished, and all of its faces are flat so that you can check squareness and measure distances effectively.

This iGaging double square also has scales of 1/8-inch, 1/16-inch, 1/32-inch, and 1/64-inch, which is useful in a variety of woodworking and construction tasks.

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  • It is a light tool.
  • Its graduations are easy to read.
  • Its black-on-silver contrast is excellent.


  • It has challenges with quality control.

5. PEC 7105-406 Double Square 6″

PEC 7105-406 6 in 4R Double Square

The PEC 7105-406 is also a versatile tool with decent quality and should be given consideration for marking, setting, and transferring precise measurement. This 6-inch double square is a precision layout square with the 4R graduation style.

The tool’s blade is made of appropriately hardened and tempered steel and finished with satin chrome. This is an excellent choice for such a tool. This tool is also described as hard, sturdy, and resistant to wear and corrosion.

It’s a basic and elegant tool that gets the job done. It has a well-machined surface and is quite durable. This tool is comfortable to hold and is accurate. If you check it with benchmark squares, you’ll see that it’s a yes.

In addition to its micro-fine characteristic, this double square’s graduation has a black-on-silver contrast. This is the sort of quality you would want and we can tell you right now that it is very clear and will remain that way throughout the tool’s useful life.

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  • It has lightweight
  • It is made from a hardened and tempered steel material.
  • Its graduations are clear to see.
  • It comes with the 1/8, 1/16, 1/32/, and 1/64 scales.


  • No spirit level

6. PEC 7104-404 Double Square 4″

PEC 7104-404 Double Square 4 inches

This is another 4-inch double square you can choose from on our list of the best double square. The tool’s etched graduation is the first feature we admire about it. Double squares are used to measure and transfer length in addition to assessing the squareness of inner and outside borders, so having a tool with permanent graduation is something to look forward to.

This double square is attractive in general. It has a cast iron head that has been finely ground to federal specifications, as well as a completely hardened steel blade with a satin finish.

This double square is only 4-inches long, making it compact and easy to take about in your pocket. It has scales of 1/8-inch, 1/16-inch, 1/32-inch, and 1/64-inch, making it ideal for all of your construction needs.

It’s also useful for setting up machines, jigs, and laying out joints.

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  • constructed of long-lasting material
  • comes with useful scales
  • its graduation is indelible
  • quite light in weight

7. Fowler 52-435-006-0 Double Square 6″

Fowler 52-435-006-0 Double Square Cast Head with 6 inches Blade

In this case, Fowler 52-435-006-0 is a great option for projects requiring a double square larger than 4″ like in the layout of joints. When you need to check for inner and outer squares, measure small distances, or transfer measurement, the Fowler 52-435-006-0 double square is an excellent option.

In terms of size, the blade is 6 inches in length and is large enough to be used for joint layout and measurement. The precisely ground satin chrome blade is composed of hardened and tempered steel, while the head of this suitable tool is built of highly robust cast iron.

The 1/8-inch, 1/16-inch, 1/32-inch, and 1/64-inch scales are marked on the blade of this instrument, according to the 4R graduation system. Because of its modest size and good black-on-silver contrast, the graduation is also very visible.

Machinists, toolmakers, and patternmakers can use this Fowler 52-435-006-0 double square.

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  • It’s not heavy.
  • It includes a 4R scale, which is useful for construction.
  • It’s designed to be precise.


  • No spirit level

8. Starrett 13MC Double Square 150 mm for Larger Metric Projects

Starrett Reading Double Square with Hardened Blades, Millimeter Reading - 150mm Blade Length - 13MC

This model should be your tool of interest if you work mainly with the metric measurement system and need a larger-sized double square. This Starrett 13MC, like many other Starrett products, demonstrates strength, quality, and robustness, and it is built in the United States, as expected.

This tool may be thought of as a metric version of the Starrett 13C as it comes with a blade overall length of 150 mm, which is roughly 6 inches.

Machinists, toolmakers, and patternmakers frequently employ the Starrett 13MC. It’s ideal for measuring and transferring precise short distances, as well as testing squareness. It comes with two scales: mm and 1/2 mm on its blade.

This double square is nicely polished and machined, as well as being quite precise. Because the tool’s faces are properly squared, you can be confident of its excellent precision. Furthermore, because of its hardened blade, it is a durable tool that has been strengthened for rigorous use. It features a satin chrome finish that prevents corrosion.

It has a strong black-on-white contrast that makes the graduation quite visible and a level vail that is applicable to check for alignment.

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  • It’s not a big tool
  • Has easy-to-read graduations
  • It’s a precise square
  • Constructed of a long-lasting substance
  • Applicable to ensure that the job is straight
  • Built-in spirit level at the head


  • Pretty expensive

9. Starrett 13MA Double Square 100 mm for Smaller Metric Projects

Starrett 13MA Double Square 100 mm for Smaller Metric Projects

If your work requires you to get a portable metric double square, then this Starrett 13MA is your go-to. The Starrett 13MA is another great product on our list of the best double square. It is a smaller version of the Starrett 13MC with a total blade length of 100 mm. it is a metric tool hence it is measured in millimeters.

The blade of this Starrett double square is made of steel which has been hardened then finished with satin chrome. With a satin chrome finish, you can be assured that the tool is well protected from corrosion. It also reduces the reflective property of the tool so that it does not blind the eye when taking your reading or measurement under a light source.

The blade is graduated in millimeters and 1/2 millimeters on both sides, which is useful for measuring and scaling. It is small and light enough to put in your pocket considering its dimension. The ruler’s end is precision machined and may be used to evaluate dovetail squareness.

As with other Starrett goods, this tool is accurate, and you should not hesitate to get it, especially if you want a small-sized metric double square.

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  • Lightweight.
  • Portable tool.
  • Made and finished with very durable and wear-resistant material.
  • It has a good black on white graduation contrast.


  • It’s a bit costly.

Things to Consider Buying Double Square

1. Material and Finish

On our list of the best double square, most of the double squares come with a blade made from hardened and tempered steel and a head made from cast iron. They are robust and durable materials and have been built to last very long.

Satin chrome is what most of the double squares on our list are finished with because they make the square corrosion-resistant and help to improve the hardness of the tool. Furthermore, they are not very reflective so as you would expect there is less glare from tools finished with this material. This is very helpful especially when reading of or marking measurement under a light source.

You must also note that because the material is made of cast iron and steel, they are still subject to rust despite that they are finished with satin chrome. If you would work in a highly corroding environment you should keep a coat of WD-40 on it to keep the tool functioning.

2. Size

The 4-inch and 6-inch squares are very prominent on our list of the best double squares. It may be not easy to decide which of the two to choose. Longer blades cover more length, so they are better for larger projects but on the other hand, they will be difficult to use in tight, difficult-to-reach areas. As a result, they may be completely useless when checking the squareness of tight corners. This is one of the factors to keep in mind when selecting your new double square. It is best to choose your double square based on the project you are working on.

If you work on a variety of project sizes, you should consider purchasing more than one double square size.

3. Ease of Sliding and Locking the Head

Due to the adjustable joint between the blade and the head of this double square, there is a chance that the two will misfit or the screw will not screw properly due to friction.

When you get your double square, the first thing to look for is if the blade glides easily on the head when the locking mechanism is fully open. This is critical because if there is friction, the blade will quickly wear out and the markings may wear off.

When you get your double square, the first thing to check is whether the blade glides easily on the head when it’s unlocked or not. This concern is critical because the blade will quickly wear out due to friction (glides) and the markings may wear off.

After that, lock the blade to see whether the knob still slides on the thread or not. In addition, see how solid the blade rests when the knob is completely locked. The blade should be firm and free of wobbling, and the knob should slide effortlessly on the thread. If it wobbles, you will not get an accurate measurement, thus the square is worthless; nevertheless, if the knob slides over the thread with difficulty, you may need to replace the square, or it might be fixed with some fine-tuning and oiling.

We have described the strengths and weaknesses of the many double squares on our list of best double squares, so you should take your time to choose the one with the best quality. If you are still undecided, go for our all-around best double square because it has all of the best qualities.

4. Graduation Unit and Scale

The double square is available in both metric and imperial units. The Starrett 13MC and the Starrett 13C double squares are examples of two similar tools made by the same manufacturer but with distinct measuring systems. It is important not to order one for the other. If you operate mostly in inches, you should use the imperial system, whereas those who work in millimeters should use the metric system.

Most of the double squares on our list have the 4R scale. This graduation system includes the 1/8-inch, 1/16-inch, 1/32-inch, and 1/64-inch scales for the imperial unit squares. Also, there is the mm and ½ mm graduation on the metric unit double square. These are great when measuring and during construction by woodworkers, carpenters, machinists, patternmakers, and tool makers so your square should come with either of these scales.

Final Thought

The double square is among the tools every woodworker, machinist, carpenter, or toolmaker should have in their tool collection. You would need a double square to transfer measurement easily and to check inside and outside squares. The double square compliments other woodworking tools to make your project a total success.

We have broken down the list into an easy-to-understand bunch and explained why each tool made it to our list of best double squares. We also discussed in the buying guide some additional information you should know before you pick your next double square.

On our list of the best double square, the Starrett 13C is the overall best. It has all the qualities that you can expect from a double square plus it has Starrett quality radiating from it. We strongly recommend this double square. However, for budget choice, you could consider the iGaging 34-4466-S Double Square, which is quite cheaper and durable. On the contrary, if you work on smaller projects and need something more portable than the Starrett 13C, the Starrett 13A is the best choice.

If finally, you need something larger than the Starrett 13C (this is the largest model we have on this list), then you should check out combination squares. Double square and combination square share some similar points but they are different in some areas as well. Maybe, you’d better off using the combination square. And don’t forget to check the accuracy of your double square with higher precision square before relying on it to do precision and accurate jobs.

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