Selection of drill bits

Drill Bit Size Guide – What Size Do You Need for a 10-32 Tap?

Drill bits are essential tools for a wide range of applications and projects. While they seem fairly straightforward, knowing how to size them appropriately for the job ahead is essential for achieving efficient and accurate results.

This guide to drill bit sizing will explore the significance of choosing the correct size, and, more importantly, it will explain what size drill bit is required for a 10-32 tap. We will also cover tips for accurate drilling and selecting the right drill bit for working with various materials.

So, let’s dive right in!

What Is the Importance of Understanding Drill Bit Sizes?

Threaded tap drilling into wood

As you may know, each drill bit size is designed to ensure the accurate drilling of holes. If you use a drill bit different from the relevant size for the diameter hole you want to create, your work will not be accurate.

When you are working on a job that requires drilling holes to specific measurements, having the exact drill bit size is essential.

Using the correct drill bit size also makes your work more efficient. It speeds up the entire process and prevents unnecessary wear and tear on both the drill bit and the material it is being used on. You also need to use the correct drill bit size to make sure it is compatible with the tool you are using.

What Is a 10-32 Tap?

A 10-32 tap is a specific type of tap that is used for creating threads. It can be used for various materials, including metal, wood, and plastic surfaces. The 10 refers to the diameter of the screw being used, while the 32 relates to the precise number of threads per inch.

10-32 taps are used for applications requiring precise fastening, so you must purchase the perfect drill bit.

What Size Drill Bit Do You Need for a 10-32 Tap?

To find the drill bit size you will need for a 10-32 tap, refer to a tap drill chart. These charts provide a thorough reference point for determining a specific tap's appropriate drill bit size.

The standard recommendation for a 10-32 tap is typically a #21 drill bit. We always recommend referencing a tap drill chart before you begin drilling, but a #21 drill bit is a good option if you do not have access to one.

What Do Drill Bit Sizes Mean?

No matter what you are doing, it is essential to understand the drill bit sizing system. In most cases, drill bits are identified by their fractional size, numbered sizes, or measurements according to the metric system.

In the case of a #21 drill bit, which is the size you would almost certainly need for a 10-32 tap, the drill bit has a diameter of 0.159 inches or 4.0386 millimeters. While most manufacturers list the bit as a #21, others might label it as a 4.0386 or 4.04 mm bit.

For more information, we recommend reading our Drill Bit Size Guide, which provides a wealth of information as well as a handy drill bit size chart.

What Should You Do Once You Have Selected the Correct Drill Bit?

Hand holding five different drill bits

Once you have your drill bit selected and you are sure that it is a high-quality bit made from materials that are appropriate for the surface you will be drilling, you can begin.

Pre-drill the hole by securing the workpiece and wearing the correct safety equipment, like safety goggles and gloves. Pre-drill the hole by applying the appropriate pressure for the material you are drilling.

This will create the threads you need within the hole. Once complete, insert the appropriate screw and ensure you have completed your 10-32 tap.

Tips for Accurate Drilling

  • Always mark your drilling spot ahead of time.
  • Consider using a drill guide or drilling jig.
  • Begin by drilling a small pilot hole.
  • Always use the correct drill speed for the material you are working with.
  • Secure the workpiece before you begin drilling.
  • Always try to apply even and consistent pressure when you are drilling a hole.

Consider cutting and drilling fluid if you are drilling dense and hard materials, like thick metals and heavy-duty plastics. We recommend Tap Magic EP-Xtra Cutting Fluid. It helps drill accurate holes and can protect your drill bit by reducing friction and heat during the drilling process.

Which Types of Drill Bits Should You Use for a 10-32 Tap in Different Materials?

While the size of the drill bit you use for a 10-32 will not change, you may need to ensure that the type of drill bit you use can handle the material you are working with.

Here are the commonly accepted drill bit types for some of the materials you may want to drill.


Typically, you should use a brad point drill bit or a Fostner drill bit with wood. Brad point bits are helpful when accuracy is essential, while Fostner bits are better for flat surfaces where you need the tap to sit perfectly flush.


Metal is a reasonably difficult material to drill, so make sure you use a drill bit made of high-speed steel or cobalt. A twist drill bit or step drill bit should do the trick if made from durable metal.


With softer plastics, you should be able to use a brad point drill bit. However, dense plastics could require a spade drill bit.

While choosing the correct size of the drill bit is essential, it is always important to ensure that the drill bit you have chosen can handle the materials you are working with.

Where to Purchase Drill Bits for a 10-32 Tap

Regardless of what type of work you are doing, you want to purchase high-quality tools that will last. Simple Weld carries a range of drill bit sets that can cover you for just about any type of tapping project.


Not only are the drill bit sets available in various materials and sizes, but they are also available at the best prices you will find anywhere. Click the following link to shop: SIMPLE WELD Drill Bits.

Final Words

Remember, always consult a tap drill chart if you need help determining which size drill bit you need. Use the tips above, and you should be fine.

For more information, we recommend reading Drill Bit 101 - How to Put a Drill Bit in a Drill. You can also read Finding the Right Drill Bit Size for a 3/8” Tap.

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