What Size of Drill Bit Should Be Used For a 10-24 Tap?

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If you’re new to working with tools and find yourself daunted by the prospect of determining the appropriate drill bit size for a 10-24 tap, as well as navigating the intricacies of the drilling process, fear not.

With precise calculations and a bit of guidance, these tasks can become much more approachable. So, let me guide you into the world of accurate measurements and insights!

Drill Bit Size for a 10-24 Tap

The appropriate drill bit size for a 10-24 tap is a #25 drill bit with a 5/32″ diameter.

drill bits for tap

When dealing with a 10-24 cap, it’s crucial to understand that it comes in two distinct thread counts. This distinction inherently implies that the drill bit size required for each thread count varies significantly. 

In a world brimming with various tapping specifications, it’s quite common to encounter challenges in recalling the precise drill bit size for each scenario. To alleviate this challenge, here’s a comprehensive sizing guide specifically tailored for a 10-24 tap. 

How to Find Out the Drill Bit Size for 10-24 Taps

The first step in determining the drill bit size for a 10-24 tap is to comprehend the size variations of the tap.

10 and 24 in 10-24 are two distinct sizes with which you must work. Consequently, you will require separate drill bits to work with various sizes.

To determine the size of the tap, you must first examine the exact length or the thread pitch. After looking at the dimensions, it is simple to decide which size fits your tap size.

10-24 Tap Sizing

You must evaluate several parameters and dimensions for the sizing of 10-24 taps.

tapping a hole

How to Calculate the Size of the Tap Drill

DH = DMB -.0130 (percentage of desired full thread / Ni), where DMB is the diameter and Ni is the other component of the tap.

Why Do 10” and 24” Tappings Require Different Sizes?

Both taps have the same diameter, but their thread pitch is distinct. The thread pitch is defined as the number of threads per inch.

brushless drill torque setting

The thread pitch significantly affects the length of the tap. In the case of a 10′′ tapping, the threads per inch will be less than those of a 24′′ tapping, resulting in the need for different-sized drill bits.

If you fail to calculate the size of the drill bit, the hole’s dimensions will be incorrect and will prevent the machine from operating correctly.

How to Start Drilling With 10-24 Tap

  1. Obtain the necessary dimensions and select the appropriate drill size.
  2. Use clamps to prevent slippage or rotation.
  3. Place masking tapes on the material to mark the drill hole location.
  4. Place the drill at a 90-degree angle and ensure that it is perpendicular to the metal [1].
  5. Do not forget to test the drilling method on scrap material.


What is the pitch of a 10-24 tap?

The pitch of a 10-24 tap is 0.1629 inches. The screw pitch indicates how far apart the threads are from one another or how tightly the spiral is wound. To determine which screw you require, you must know both the size and the material. The right size will help prevent any occurence of stripped wood screw hole in the process.  

Why drill a pilot hole?

Drilling a pilot hole will prevent material splitting. There is significantly less wedging when a screw is driven into the spot where a pilot hole is drilled. Plastic, wood, and concrete require a pilot hole because they are not particularly difficult to work with.

Why are most drill bits kept at a 118-degree angle?

When working with softer materials such as wood, drill bits are typically maintained at an angle of 118 degrees. This angle sharpens and focuses the drill’s point. It also reduces chisel wear, though this is not recommended for more rigid materials.


Navigating tap sizes can indeed be perplexing, leaving many individuals wondering about the appropriate drill bit size for a 10-24 tap. In essence, the dimensions of a tap encompass two distinct numerical values, requiring only a modest grasp of a handful of formulas and a readiness to embark on precision drilling. 

By understanding these key principles, you can confidently embark on your tapping projects with the assurance of accuracy and efficiency.

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Robert Johnson is a passionate furniture maker & carpenter, sought after for his knowledge on the craft.
You’ve probably seen his down-to-earth wisdom in USA Today, Bobvila, Family Handyman, and The Spruce, where he has shared commentary and guidance on various woodworking topics.

Robert is the brain behind Sawinery, where he aims to share tips, tricks, and a passion for all things carpentry.

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