M6 Screw

What Size Is a Standard M6 Screw?

Bolts and nuts are very fundamental fastenings and essential in assembling equipment, furniture, machinery, and much more. In most assembling processes, you will need to use the right fastening. We will help you learn the standard size of the M6 screw and other things you need to know about screws, nuts, and bolts that we think are important. Also, you will dispel any confusion when it comes to the sizes of screws. In addition, you will get to know how different sizes are determined. 

The screw concept

The screw concept has been in existence for more than 2,000 years. It started around 200 B.C, and since then, the idea has played a great role in industries in holding different components together. Without bolts and nuts, it can be impossible to join equipment together perfectly. 

Metric bolt sizes

Metric bolts and nuts are referenced using “M” sizes. A few examples include M3, m12, M8, and M6. The size of a metric nut or bolt is specified more accurately using its diameter, length, and pitch dimensions. The diameter is measured in millimetres. For nuts, the common size dimensions used are pitch and diameter.  Below is an example of  M6-1.0×20 what each number and letter means:

M6-1.0×20 metric bolt specifications

The bolt specification breaks down as follow:

  • The letter “M” shows that this screw uses a metric thread.
  • The number 6 is the nominal diameter of the screw shaft, which is determined in millimetres.
  • The number 1.0 is the screw’s thread pitch: distance between threads, also in millimetres.
  • The final number is 20, which is the length of the screw in millimetres. 

It is very common to find that the abbreviation of metric bolts omits the pitch. Using the example above, when the pitch is omitted, the abbreviation would look like this: M6-20. When this happens, it means that the bolt is crafted with a coarse thread. From the example, the diameter is 6 while the length is 20. 

Sizes of metric bolts’ holes

The diameter of these metric bolts is not actual. The actual diameter is slightly higher than the diameter of the screw shaft. This means that our M6 screw would have a shaft slightly below 6 mm, and it will fit well through a 6 mm hole. It is recommended that you dig a hole that is somewhat larger for allowance and any misalignment. 


When cutting a thread is necessary, the size of the hole needs to be slightly smaller in diameter to enable the tapping of the thread. You can determine the perfect tapping hole by deducting the thread pitch from the bolt’s diameter. For example, an M6 screw with a thread pitch of 1.25 mm would need a 4.75 diameter hole to be effectively tapped. On the other hand, if the M6 bolt has a 1 mm fine pitch thread, the hole’s diameter that needs tapping would be 5 mm.

What is the size of an M6 screw?

M6 is a metric 6 mm screw. The outside diameter of the screw’s thread is 6 millimetres. The metric rack of this screw is M6 x o.1 mm, where the number 0.1 stands for  0.1 threads per millimetre. 

Screw head types

Most head types are either round, flat, or oval. There exist other options as well.

  • Flat-head screws are designed with a flat top and an underside that is conical in shape. The design allows the wood screw to sit flat with the workpiece to create a smooth surface. 
  • Oval head screws are also designed with a conical-shaped underside just like their flat head counterparts. However, they have an attractive top that slightly protrudes above their surface. 
  • Round-head screws are designed with a flat head’s underside with a domed top above the workpiece’s surface. 

Basic types of screws

The style in which a screw is designed will determine its function. The material from which a screw is made will also determine where you should use it. Although there are various types of screws, there are three main ones that are commonly used. They include the following:

  1. a) Sheet metal screws: These types of screws are threaded up to the head, and there is no interruption in their threading.
  2. b) Drywall screws: They tend to be curved at the point where the head connects to the shaft to protect the screw from tearing.
  3. c) Wood screws: This is a standard screw that forms its internal mating thread in a piece of wood or any other resilient material. The threads help to hold two components open rather than fully closing them together. 

From the names of the screws, you will know the screw to use. However, there are other factors that you need to consider when buying the right screw for your work, such as length and size.

Which screw should I use?

Each type of screw has its distinctive functions. No way two kinds of screws can be the same. Before buying screws for your project, you should consider the following things to get a perfect screw.


Different screws are designed to fasten different materials. You should first determine the material of the components that need to be joined together. Also, consider the material from which the screw is made. Some of the materials used to make screws include steel, copper, aluminium, and titanium. 

Thickness and length

Choose a screw long enough to pass through your material at least halfway to the next material for a more secure grip. 


If you want your fastening to last, you may want to buy screws made from more sturdy metals. However, if you are working on a temporary structure, you might not need to buy expensive screws. 

Coating options

For more improved screw quality, consider screws that come with premium coating. Some have more decorated coatings which are mainly used to connect some decorative items. The coating makes screws more flexible and convenient. 


Screws are available in different sizes, and M6 is one of the sizes. This screw comes in various lengths and pitches, and your choice will depend on your workpiece. With this information, you will be able to fasten your components better and effectively. 


About Mat

A complete novice trying to navigate in the world of DIY. I bought my first home about 2 years ago & ever since I've been trying to research & learn how best to tackle common household problems.

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