What Size Drill Bit for M8 Masonry Bolt?

The standard size drill bit for m8 masonry bolt is 8mm. But if the material is a hard surface like concrete, you will need a slightly larger drill bit (9mm) specifically made for masonry bolts. And if it’s a softer material like softwood or plaster, a smaller size drill (8mm or smaller) bit might be more appropriate.

I am here with a detailed guide that will help you choose the correct size drill bit for the M8 masonry bolt. So, simply scroll down and keep reading to learn all about masonry.

What does M8 stand for?

M8 stands for 8mm metric threads. Here the letter ‘M’ signifies that it has metric threads, and”8″ refers to the bolt’s diameter in millimeters. This size drill bit will cause the least damage and will securely hold the bolt in place.

How do you use m8 masonry bolts?

M8 masonry bolts are a valuable part of your home and essential for your safety. They are a versatile and essential piece of hardware for masonry projects. Usually, people use them to secure wood, concrete, and other materials in place. Let’s know the simple steps to use them:

1. Hold the bolt with one hand and use the other hand to twist the bit until it’s tightly attached to the bolt head.

2. Keep your fingers close to the head of the bolt when installing, so you don’t slice them on the sharp edges of the bit.

3. Use a M8 drill bit and install masonry bolts in wood, concrete, and other materials.

What size hole do you drill for an m8 bolt

Drilling holes is never easy. You might end up drilling too big or too small, which can cause several problems. For example, you might not be able to fit the bolt through the hole, and the hole might become damaged over time.

If you have an m8 bolt to install into a threaded hole, you need to drill slightly larger holes  (9mm). Because a smaller hole can cause the bolt to become loose and eventually come out of the socket. This could lead to serious damage or even injury. So, when drilling for bolts, drill the appropriate size hole so it seats properly and accommodates the M8 bolt head better.  Let’s know about some more sizing details that you should consider while drilling a hole for an M8 bolt.

clearance hole sizes, standard or coarse thread pitches along with fine thread pitches and their corresponding tapping hole sizes:

         Size                   Clearance Hole (mm)         Thread Pitch (std)Tapping Drill (std Pitch)         Thread Pitch (fine)Tapping Drill (fine pitch)

Standard metric spanner, allen key and  Socket Key sizes:

Size                          SpannerAllen KeySocket Size

How to drill for M8 Masonry bolts

Drilling M8 Masonry bolts can be a frustrating experience if you don’t have the right tools and don’t know how to drill. First, identify the location where you will be drilling. Next, mark the location on the bolt using a pencil. Finally,  use a quality bit appropriate for the type of masonry you’re drilling with.

For mortar and brick, use a round-head bit; for stone or concrete, use an attachment designed specifically for this purpose and drill. Don’t shake hands; hold the bolt steady so you don’t slip or lose control.

When to use m8 masonry bolts & its benefits

M8 bolts are usually used in situations where fast, secure installation is required, such as in applications where aesthetics or a tight time deadline are important factors. M8 bolts are versatile and can make your masonry projects easier and faster.

They have been used in brick and stone construction because of their reinforced heads. They’re also great for attaching wood framing members to masonry walls or floors.

You will find them in various sizes to find the best fits for specific applications. 

You can tight them using your hand tools or an electric drill, making them perfect for professional and DIY users.

In addition, they offer good corrosion resistance and can hold a great deal of weight before failing.

Other considerations before using M8 masonry bolt?

  • Consider the size of the bolt head and-or nut before selecting them.
  • Use the right size drill appropriate for the bolt you’re drilling. If you’re not sure which bit to use, consult a professional. 
  • Make sure the drill bit you purchase has a shank diameter of at least 1 inch so that it firmly grips the bolt head.
  • Make sure your drill is powerful enough to penetrate the masonry deeply without causing damage. 
  •  Always wear safety goggles when drilling, and be extra careful of your surroundings, especially when working near water pipes or electrical cables. Never try to remove the bolt while they’re still connected!
  • Carefully read the manufacturer’s instructions to learn more specific information and follow them.


After reading this blog, I hope now you clearly know what size drill bit to use for M8 masonry bolts and when to use them. I have also answered some related questions that may roam in your mind.  If you have something more to know, feel free to comment below or send me an email.

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