What Size Drill Should You Use for a 1/4 20 Tap?

If you’re wondering what size drill to use for a 1/4 20 tap, the answer is 7/16. This size will give you the perfect fit for the tap, and will ensure that your threads are nice and tight.

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To ensure that your drill is the correct size, you need to measure the diameter of the bit. The most common size for a 1/4 20 tap is a 7/16 or an 11/64 drill bit. These drill bits are commonly used for general-purpose drilling in a wide variety of materials.

Types of Drills

There are two main types of drills: twist drills and milling cutters.

Twist drills are the most common type of drill. They are used to create circular holes in a workpiece by drilling around a central point. The size of the drill is determined by the diameter of the hole it will create.

Milling cutters are used to create slots, grooves, and other shapes in a workpiece. They come in many different shapes and sizes, depending on the desired application.

Twist Drill

Twist drill bits are the most common type of drill bit and are used for a wide range of drilling applications. They are named after their spiral fluted design that helps to clear chips and debris as you drill. Twist drill bits are available in a wide range of sizes, from small micro bits used for electronics up to large bits used for construction drilling.

Brad Point Drill

A brad point drill bits are used to drill precise, clean holes in wood quickly and easily, without walking or skating. They are the best choice for dowel holes, pilot holes for screws or large nails, and any other time you need an accurately sized hole with smooth sides.

The sharp point of a brad point drill bit starts the hole precisely where you want it, and the margins cut cleanly away from the sides of the hole as it goes, leaving smooth edges all around.

Spade Drill

If you’re looking for a fast way to drill a hole in wood, a spade drill is your best bet. A spade drill is also known as a paddle bit or a ship auger. It’s a type of bit that has a turned tip and cutting lips, and it’s used in a power drill. The spade drill is designed for drilling large, quick holes in wood, and it can be used with either hand-held or machine-driven drills.

Drill Sizes

The most common size tap drill for a #20 (1/4″)tap is .234 No. 53. This is used in almost all applications where there will only be light loads on the thread. If using this tap in an application were there will be heavy loads or shock loads on the thread, you should use the next larger size drill, which would be a #31 (7/64″). This will give the root of the thread more meat to grip onto, and prevent the thread from stripping out under heavy loads.


Before you start drilling, you need to determine what the right drill size is for the tap you’re using. This is important because if the drill is too small, the tap will break. If the drill is too large, the hole will be too big and the thread will be weak. The perfect drill size for a 1/4 20 tap is .1500

Types of Taps

There are four basic types of taps: taper, plug, bottom, and spiral-flute. Each type is designed for a specific application.

Taper taps (7 to 10 pitch) have a long, gradual taper at the tip and are used for starting threads in through holes. A taper tap has no chamfer on the outside diameter (OD) of the tap.

Plug taps (3 to 5 pitch) also have a long taper at the tip, but they have a chamfer on the OD of the tap. This chamfer starts threads more easily than a taper tap and is used most often in through-hole applications.

Bottom taps (2 to 3 pitch) have little or no taper and are used for starting threads in blind holes. A bottom tap has no chamfer on the OD of the tap.

Spiral-flute taps (10 to 20 pitch) are used for aggressive drilling and tapping operations in through holes or blind holes. The spiral flutes help to clear chips more effectively than straight flutes and minimize Tap breakage

Taper Tap

A taper tap has a gradually tapered body to help it start the threading process. The taper portion of the tap is about 4 to 5 threads long. A taper tap is used when starting a thread in a blind hole. It can be used in through holes, but the bottoming tap is a better choice in most cases. A taper tap has little or no chamfer on the tip.

Bottoming Tap

A bottoming tap, also known as a plug tap, has a slightly longer taper than a taper tap. This design allows it to cut threads all the way to the bottom of a blind hole. A bottoming tap is used when threading a hole that does not need to be tapered and when threading to the bottom of a blind hole is necessary.

Tap Sizes

The following table lists the recommended tap drill sizes for various threads per inch (TPI) values. To determine the right size drill bit to use, find the TPI of the thread you’re using in the left-hand column of the chart, then match it with the correct drill bit size in the center column. For example, if you’re using a 1/4-20 thread, you would use a #7 drill bit.

Drill Size for a 1/4 20 Tap

When it comes to choosing the right size drill bit for a 1/4 20 tap, there are a few things you need to take into consideration. The first is the type of material you’ll be drilling into. The second is the thread count of the tap. And the third is the tap drill size. With that said, let’s get into the details.

Drill Size for a Taper Tap

For a taper tap, the recommended drill size is 1/16″ smaller than the tap size. For example, for a 1/4-20 tap, you would use a 3/16″ drill bit.

Drill Size for a Bottoming Tap

For a bottoming tap (1/4-20), you should use a #7 drill bit.