Drill Bit Sizes report

Drilling is the process of creating a hole. Tapping is a technique for cutting threads in the hole. Therefore, drill bits and tapping tools are often used to manufacture parts with threaded holes sequentially. When choosing drill size and tap size, there is a standard size conversion table for reference.

When producing custom CNC machined parts in the United States, threaded holes are usually required to fasten the finished product or facilitate construction. One of the most common ways to make threaded holes is to drill a hole of the right size with a drill bit and tap it with a tap. People need a drill and tap size table to determine a suitable tap for a specific thread size or a good fixture for an existing hole.

Having the correct drill bit sizes on hand for your particular repair or building task is essential for any seasoned carpenter or weekend-DIY’er. Knowing just what size you need to use for the hole you’re making is also necessary. The following article provides a detailed drill bit size chart for reference and a drill bit buying guide.

Drill Bit Size Charts

The drill size chart lists standard size drill bits in several measurement systems, including fractional, metric, wire gauge number, and letter. Decimal sizes are measured in inches, while metric sizes are measured in millimeters. The wire gauge and letter system refer to the increase in the diameter of the tool when the wire gauge decreases from 107 to 1, and then continues from A to Z.

Standard metric drill bit sizes

Diameter of the bit in terms of standard metric lengths.

Fractional inch drill bit sizes

The sizes are written as irreducible fractions. ANSI B94.11M-1979 sets size standards for jobber-length straight-shank twist drill bits from 1/64 inch through 1 inch in 1/64 inch increments.

Wire gauge drill bit sizes

Letter drill bit sizes: the sizes are indicated in letters, from size A (the smallest) to size Z (the largest). Number and letter sizes are commonly used for twist drill bits rather than other drill forms.

Drill Bit Types

Most nice sets include anywhere from 12-30 pieces of standard drill bit types. Various bit types exist for a wide variety of applications, particularly what material you are drilling into. For the sake of simplicity, we suggest you should have a basic multi-purpose set, such as a typical 29-piece set. For most drill bit types, the angle of the point helps determine what type of material the bit can drill. Flatter points, such as those with 135-degree angles, are suited for drilling into harder material. Bits with steeper points, such as those with 118-degree angles, are suited for softer material. The following are common drill bit types in daily life:

Twist Drill Bit

A twist bit is the most common type of drill bit for home use. It works for general-purpose drilling in wood, plastic, and light metal.

Brad-Point Drill Bit

A brad-point bit is designed for boring into wood. The brad at the center of the bit tip helps position the bit precisely for accurate drilling and produces a clean exit point in the workpiece.

Auger Drill Bit

An auger bit, another type of wood-boring bit, has a screw tip that starts the hole and pulls the bit through the workpiece to create a clean hole quickly. These bits can be as long as 18 inches. As with the brad-point bit, large flutes help remove chips and dust.

Self-Feed Drill Bit

A screw at the tip of the self-deed drill bit helps position the bit and draws it through the workpiece. However, it does not have the standard flutes of a twist bit. It would be best if you pulled the bit back periodically to clear away chips and dust.

Installer Drill Bit

An installer bit is a specialized twist bit designed for installing wiring like what's used for entertainment or security systems. The bit can be up to 18 inches long and drills through wood, plaster, and some masonry. People can insert a wire into the small hole in the bit and use the bit to draw it back through the hole you bored.