What Size is a Number 7 Drill Bit? [A Simple Guide]

Drill bit sizes play a crucial role in any drilling task. Having a good understanding of the various sizes and their uses is essential for achieving accurate and efficient results. In this guide, we will explore the size of a number 7 drill bit and provide valuable insights into choosing the right drill bit for your specific needs.


Drill bits are numbered from 80 to 1, with 80 being the smallest and 1 being the largest. This numbering system allows for easy identification of different drill bit sizes. In this guide, we will focus on the size of a number 7 drill bit and discuss its measurements in detail.

What Is A Number 7 Drill Bit?

A number 7 drill bit is relatively large compared to other drill bit sizes. Its size corresponds to 0.2010 inches or 201/1000 as a fraction. It is important to note that standard fractional drill bits do not precisely match the size of a number 7 drill bit. However, by rounding 201/1000 to the nearest 1/64 accuracy, you can find the closest gauge wire equivalent.

Drill Bit Sizes

Drill bits come in a wide range of standard sizes, and it is crucial to choose the right size for your drilling task. Popular drill bit sizes include 9.53mm and 12.7mm, while smaller drill bit sets may range from 0.3mm to 16mm. Maximum sizes can vary from 1.6mm to 80mm.

How to Choose the Correct Drill Bit Size for a Screw

Selecting the correct drill bit size for a screw is essential to ensure a secure and reliable connection. Here are three options to help you choose the right size:

Option 1: Compare Screw and Drill Bit Sizes

Take the screw you intend to use and compare it with different drill bits. The drill bit should have the same width as the screw without the threads. If it matches, you have found the correct size.

Option 2: Check Labels and Packaging

Refer to the labels on the screw box or bag to find the recommended drill bit size. Most drill bits have their sizes indicated on them. For example, a number 2 screw typically requires a 1/16 drill bit, while a number 9 screw often requires a 9/64 drill bit.

Option 3: Consider Clearance and Tolerance

If you need a loose screw fit for washers or other materials, reverse the second option. Line up the screw and the drill bit, ensuring that the bit has the same width as the screw with threads. This allows for a looser fit and the use of washers if needed.

How Are Drill Bits Measured?

Drill bits are commonly measured using marks on the shank above the threads. These marks indicate the diameter of the drill bit and are often written in fractions. If there are no markings, a drill bit gauge can be used to measure the size accurately.

How Do You Put a Small Drill Bit in a Drill?

Inserting smaller drill bits, such as 1/8-inch, into a drill’s chuck can be challenging. To ensure a secure fit, make sure to fasten the drill bit tightly and avoid pushing too hard during usage. Following the manufacturer’s instructions is advisable, as some situations may require manual insertion for better control.

Should A Drill Bit Be The Same Size As The Screw?

The ideal drill bit size for a screw depends on the specific task at hand. In most cases, the drill bit should have the same width as the screw without the threads. However, factors such as tap size, clearance dimensions, and tolerance requirements should also be considered for a perfect fit.

How to Choose a Drill Bit By Type?

Drill bits come in various types, each designed for specific materials and drilling purposes. Here are some common types and their uses:

  • Twist Drill Bits: Ideal for drilling wood, metal, and plastics.
  • Screwdriver Drill Bits: Designed for use with rechargeable screwdrivers and suitable for pilot holes.
  • Masonry Bits: Intended for drilling into brick, block, stone, and concrete.
  • Spur Point Bits: Used for drilling wood and creating clean-sided holes.
  • Pilot Bullet Point: Suitable for metal, wood, and plastics, leaving minimal damage.
  • Countersink: Used to create conical recesses for countersunk screw heads.
  • Tile Bits: Designed for drilling ceramic tiles and glass.
  • Flat Wood Bits: Suitable for drilling large holes and creating flat-bottomed bores.
  • Hole Saw Bits: Used to cut large, fixed-diameter holes in wood or plastic.
  • Forstner Bits: Ideal for creating holes with flat bottoms, such as those for hinges.
  • Wood Auger: Perfect for drilling large-diameter, deep holes in wood or strong artificial boards.

What Are Numbered Drill Bits Used For?

Numbered drill bits serve as a bridge between metric and fractional sizes. They are often used with taps and allow for approximate matching to fractional sizes. While exact matches may not exist, you can refer to the next fractional bit larger than the numbered bit for the closest size.


Choosing the right drill bit size is crucial for achieving accurate and efficient drilling results. In this comprehensive guide, we explored the size of a number 7 drill bit and provided valuable insights into selecting the correct drill bit for your specific needs. Remember to consider the type of material and task requirements when choosing a drill bit, and always follow the manufacturer’s recommendations for optimal results.

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