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

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If you are inexperienced and unfamiliar with tools, calculating the size of drill bit for a 10-24 tap and the overall drilling process may appear daunting. However, once the calculations are accurate, everything will fall into place. Therefore, take your time with the measurements our pro woodworkers will share below.

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

A 10-24 cap is available in two distinct thread counts. Consequently, the drill bit size for each is entirely different. In a world with so many kinds of tapping, it is difficult to remember which drill bit size to use for each. So, we detailed everything in this sizing guide 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; their thread pitch is distinct. The number of threads per inch is the definition of the thread pitch.

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.


This tap size can be confusing and many often ask what is the drill bit size for a 10-24 tap. In sum, there are two numbers involved in determining the size of the tap and you need only memorize a few formulas and prepare for drilling.

Robert Johnson is a woodworker who takes joy in sharing his passion for creating to the rest of the world. His brainchild, Sawinery, allowed him to do so as well as connect with other craftsmen. He has since built an enviable workshop for himself and an equally impressive online accomplishment: an extensive resource site serving old timers and novices alike.
Robert Johnson
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