Best Straight Edge

Straight edge is a tool or equipment primarily used for straightness checking of a certain surface or line. But it can extend for flatness checking as well. And any light source that is put near the surface being checked will pass through if the gap exists.

Not only for straightness and flatness inspection but also for drawing precise lines. If you work with circular blades, a long straightedge will help you create an excellent straight cutting and save you a significant amount of dollars of failing.

Additionally, due to its grade of straightness tolerance, this equipment is applicable for calibration as well.

Most of the time, straight edges do not employ any graduation or markings or scales, however, it’s not possible a certain ruler is manufactured as straight as the straight edge does.

Straight edges are available in different shapes (knife edge, rectangular, etc) and lengths. They come with different grades (straightness tolerance) as well.  If you want to buy this tool, make sure you know what you need.

straight edge ruler
If you want to make a straight cut or draw a straight line, you need a straight edge

There are many products that claimed straight edges and you need to be careful. You need to know the straightness of its working surface. This post covers the top 8 straight edges that we found on the market.

Top 8 Best Straight Edges in 2023

1. POWERTEC Anodized Aluminum Straight Edge

POWERTEC straight edge tops our list for the best accuracy and value for money. It can check flatness to within 0.001 inches over its length. Besides, this product is available in different sizes to choose from. You can find 18”, 24”, 38”, and 50” long POWERTEC straight edges.

This POWERTEC straight edge is a cost-effective alternative to determining the flatness of surfaces, including tables, engine blocks, and other work surfaces. You can also tune it up for aligning machines such as planers, jointers, and many more!

This product was engineered with lightweight anodized aluminum metal that offers long service life. It can effectively resist wear and abrasion it is subjected to during everyday use. POWERTEC Straight Edge is also ergonomically designed with a thick profile and ribbed reinforcement to enhance grip. Lastly, this equipment has a hanging hole for storage.



  • Affordable
  • Lightweight and easy to store
  • Resistant to wear and abrasion
  • Versatile – straight edge guide for flat machines, drafting tools, drawing bar, etc.
  • Equipped with a dual-sided metric and standard ruler measurement system
  • Ribbed reinforcement offers enhanced grip
    ]Hanging hole for easy storage after use


  • Measuring scale is not as accurate as it ought to have been

2. Starrett 385-36 Steel Straight Edge

Starrett 385-36 Steel Straight Edge is another cost-effective piece of equipment coming second on our list of the best straight edges. Like the first product, this one is also very accurate. It boasts an accuracy of 0.002 per square foot.

This product is a reliable ruler with many uses. It is relatively long, extending to 36 inches in length. The Starrett 385-36 steel straightedge has excelled in inscribing or drawing straight lines and checking surfaces for straightness and flatness.

Starrett 385-36 boasts portability and ease of handling. Its design, rectangular shape, and thickness allow you to use this equipment while retaining its accuracy. It is also beveled on one edge but not graduated. That, however, does not stop you from using it for taking a quick reading.

This tool is functional and also attractive with a regular steel finish.



  • Very accurate
  • Allows for quick readings
  • Portable and easy to handle
  • Retains shape and accuracy
  • Multi-functional


  • Length can be short for some applications

3. Central Tools 6431 Straight Edge

Central Tools 6431 Straight Edge could have been the best product on the market if not for its high price. This equipment comes in three different versions: 18”, 24”, and 35” straightedges. These are priced differently, but they have the same precision.

Central Tools 6431 Straight Edge is heavy-duty equipment with high-quality heat-treated steel and tough epoxy coating to resist corrosion. The steel is ¼ inches thick for stability and durability. It is built to last and withstand wear and tear from daily use.

Central Tools 6431 Straight Edge is recommended for use in the automotive industry. With feeler gauges, you can measure head, block, flywheel straightness, and other applications on both small and heavy-duty diesel engines.



  • Stable and durable
  • Very accurate
  • Resistant to corrosion and regular wear
  • Used in many applications
  • Convenient hang-up hole


  • Expensive

4. OEMTOOLS 25355 Straight Edge 24″

OEMTOOLS 25355 straight edge is more cost-effective equipment than the previous one. This professional straight edge is used together with feeler gauges in the automotive industry, where it is used for checking cylinder heads and engine blocks. It features a machined straight edge that makes inspection of flatness and distortion faster and easier.

This is a very accurate straight edge made in the USA with ¼ inch cold rolled steel. It features a black powder coating to shield it from corrosion and rust, making it one of the most durable straight edge tools on the market.

Like most straight edge tools on this list, OEMTOOLS 25355 also has a convenient hang hole for safe keeping after use.



  • Strong and durable
  • Resistant to rust and corrosion
  • Convenient hang hole
  • Relatively affordable
  • Very accurate straight edge


  • Some products come damaged or bent

5. Fulton Anodized Aluminum Straight Edge Bar

If you are looking for a pocket-friendly tool for checking flatness, Fulton anodized aluminum straight edge bar got you covered. You can use it to check if your flat surface has gaps, pits, or any other imperfection. We all know these undulations can affect the machining process. But with this tool, nothing will skip your eye.

Fulton anodized aluminum straight edge bar is best for checking power tools, jointers, table tops, wet stones, countertops, and other surfaces. You will also need it for general machinery work. What makes it the preferred cost-effective equipment is its high accuracy. It works well to detect imperfections and ensure the surfaces are flat.

This Straight edge is sturdy enough to stand upright without support. That frees your hands if you want to make any adjustments to your tools.



  • Very affordable
  • Comes in different sizes
  • Stands on surfaces without support
  • Lightweight and durable
  • Very accurate
  • Used in a wide range of applications


  • Length is limiting for some applications

6. Mitutoyo 528-103 Knife Edge Straight Edge

Mitutoyo 528-103 is another worthy piece of equipment to include on this list of the best straight edges. It features here because of its accuracy and insane straightness of +/- 0.00005 inches. However, you pay more for that property.

The blade has a black dye to make it easy to inspect and check flat surfaces for straightness. Additionally, the upper edge is coated with a gripping place for easy handling. Generally, this product is easy to use and guarantees the best accuracy.



  • Easy to handle
  • Very accurate
  • Comes with a protective sheath
  • Reliable and long-lasting


  • Expensive
  • Very short lengthwise

7. INSIZE 4700-300 Straight Edge

The INSIZE 4700-300 straight edge comes as second last on our list of the best straight edges. This measuring instrument is designed with a beveled edge and made of hardened stainless steel for durability. It is further satin chrome plated for aesthetics and to resist rusting and corrosion.

The INSIZE 4700-300 is an equally accurate tool any wood or metal worker would wish for. Despite its relatively short length of 11.8 inches, this tool is still worth considering.



  • Made of hardened stainless steel for durability
  • Satin chrome plated
  • Aesthetically attractive
  • Very accurate


  • Relatively expensive
  • Could have been longer

8. Starrett 380 Steel Straight Edge

Starrett 380 steel straight edge comes in two sizes, 12 and 24 inches long. What you choose depends on your application, but each boasts high precision. This product has an ideal thickness, allowing it to retain its shape and accuracy for a long time.

This choice is best for drawing or scribing straight lines and checking if surfaces are flat. Unlike some Straight Edges on this list, Starrett 380 does not have beveled edges or any markings. But other models from the same brand are beveled and graduated. It, however, remains easy to handle and portable.



  • Portable and easy to handle
  • Retains shape and accuracy
  • Has many variations to choose from
  • Strong and durable


  • Relatively expensive
  • Edges are slightly burred

Straight Edge Buying Guide

This tool varies in accuracy, size, shape, and use. What you buy from the market depends on the intended purpose. So, what factors do you have to consider? This buying guide provides an insight into what you should look for when buying a straight edge for any application.

1. Accuracy

The primary factor to consider when looking for a straight edge is its accuracy. Different applications require varying accuracy grades. Grade A is for inspection, B for the workshop, and AA for the laboratory. These grading systems vary from region to region. For example, the one we stated is used in the US. If you are in Europe, the different straight edge grades are 00, 0, 1, and 2. Grade 00 is the most accurate.

You also need to check the tolerance for the straightness of the straight edge you intend to buy.

2. Length

The straight edge you choose should be long enough to cover the entire length of the workpiece. Using a shorter model such as knife edge model should not be applicable for the long workpiece. It takes time. If the workpiece is small, you can switch the smaller model.

Fortunately, straight edges are of different sizes. Some are only 6 inches long even shorter, but others can extend up to 50 inches. Once again, your choice depends on the application.

3. Shape (Models)

The shapes of straight edges include the I-beam, bow, rectangular, knife edge, triangular, bevel, etc. Once again, the shape you choose depends on the intended application. If you want to check the straightness of a large flat surface, choose any tool. But if you need a straight edge for checking the straightness of dovetails on any machine tool, go for a triangular or beveled shape.

Checking straightness in a narrow-recessed channel requires a thin rectangular or knife-shaped model.


Q: Can I use the straight edge to measure levelness?

A: Yes, you can. Put the rectangular straight edge (or another model with a wider working surface) on a certain surface. The idea behind using a straight edge is to replace the surface plate which is more expensive. Check the levelness of that straight edge by using a mechanical precision level and adjust the straight edge until it becomes level. Now, you can replace that precision level with your spirit level.


So, straight edges and rulers may look similar but they are actually different. The main function of a straight edge is to provide you a straightness reference. A ruler gives you graduation for length measurement. If a product states that they are straight edge, be careful, they may be just a ruler. However, a ruler can be a straight edge if it’s manufactured with high precision. And a ruler that behaves as a straight edge can be found at precision rulers.

POWERTEC tops our list and is the best for accuracy and value for money. It is also lightweight, portable, and easy to handle and store. You spend less to buy this versatile equipment, which you can use as a straight edge guide for flat machines, drafting tools, drawing bars, and many more.

Starrett 385-36 is another cost-effective piece of equipment. Like the first recommendation, this Straight edge is also very accurate, portable, and easy to handle. It is also designed to retain its shape and accuracy for a long time.

The last recommendation is Central Tools 6431. It is highly stable, durable, accurate, and has many applications. However, it is costlier than the many products we reviewed. It can be the best choice if you have the budget.

You can use our buying guide to make an informed decision when buying an Engineer’s straight edge if the recommended ones are not what you are looking for.

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