What Size Is An M6 Bolt: Dimensions Explained [Size In Inches]

Nuts and bolts are essential fastenings used to join together machinery, equipment, furniture, and much more. In most circumstances, the right bolt size must be used.

We see the usage of nuts and bolts commonly in workshops and construction projects. But today, we will just discuss bolts.

Bolts are threaded fasteners used externally with a nut to hold two pieces of material together. They don’t rotate in the assembly process, but the nut secures it.

The screw is a threaded fastener that passes through the material to form its own thread. You’ll be able to tighten a bolt by applying torque to the head.

Without knowing the right measurements for bolts, you might find it difficult to work on machines and risk damaging them.

To avoid any complications, we will talk about M6 bolts and what their size and specifications are.

Let’s get started!

What is an M6 Bolt?

M6 bolts are used in many applications for the trade and the home. They have a hexagonal head to adjust easily, and they’re available in both full-threaded stems so that they can be used with a nut or in a tapered hole.

The M6 screw is a metric 6mm screw with an outside diameter of 6mm. It has one thread per millimeter. They are often used by HP to mount computer components but can also be found in other devices.

The measurement of M6 bolts is identified by measuring the diameter with a ruler at slightly more than 7/32″ (0.228″).

Compared to the American bolt measurement, when measuring the diameter of screws and bolts, it’s important to measure the distance from the outer thread on one side to the external line on the other side.

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This is called the major diameter and will usually be the proper size of the bolt.

How To Measure Metric Bolts?

Suppose you find yourself working with metric bolts for your next project. In that case, you will quickly realize that the part numbers and measurements are in millimeters instead of inches.

How To Measure Metric Bolts


Measuring the diameter of a metric bolt from one end to the other- so easy! The best way to do this is to have a caliper that measures in metric units.

You can use a caliper to clamp around the bolt and adjust it until it fits. It’s great for when you need an exact measurement, like when you’re assembling something!


Metric bolts are a really great way to measure the length and save time. Start from the last number in the metric measurement, the bolt head, and measure down to the end of the shank.

Do not include any part of the head in your size.

Thread Pitch

The pitch of a bolt is the distance in millimeters between threads along its length. You can calculate the angle of a bolt in seconds with a free online bolt calculator.

Consider buying a bolt gauge, a device that can help you with this process a bit more quickly!

This is challenging to many, but we’re here to help! You may also watch this video about Measuring Metric Bolts to have a better idea.

YouTube video

Standard References In Using M6 Bolts

For every bolt size, there is a standard performance and procedure. As for M6, bolts have a specific metric pitch, bolt clearance and tapping hole, standard spanner.

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Additionally, Allen key sizes, maximum torque thresholds, and standard-proof loads are a requirement.

Each detail is vital, for having at least one error may cost you a project. To avoid any problems, we will cover each one by one.

Metric Pitch

Wondering what the difference is between pitch and threads per inch? Pitch is the distance between adjacent lines.

Threads per inch are sometimes called pitch because it’s easier to say, but it’s not right—threads per inch are a metric measurement.

Although the ISO standard defines different threads, two are most commonly used in most machinery: standard and fine.

The others are only used in special equipment such as precision instruments, optical instruments, etc.

Pitch refers to a thread’s distance between two adjacent lines. Thread diameter is the outside diameter of a single thread.

Common diameters and pitches are listed in the table.

M6 Bolt Clearance and Tapping Hole

Metric bolts are made in fractions of their stated size, so a 16mm bolt will fit through a 16mm hole. If you want to make sure your parts line up properly, it is important to drill bolt holes slightly larger.

These are known as clearance holes.

The table provides an overview of the typical clearance hole sizes that are common in most holes. The guide will help you to determine the correct tapping hole size for each type of standard and fine pitch thread.

If you’re using metric threads, it’s easy to work out the tap drill size because it’s just the bolt diameter minus the thread pitch, so a standard pitch M16 bolt has an angle.

Standard Spanner and Allen Key Sizes

Want to get started with your project quickly and safely? Check out the table below to find out more about the normal range of bolt and nut sizes.

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When it comes to working on fasteners, using a ring spanner is the best option.

It’s small enough to fit into tight spaces. It will help you avoid those frustrating moments when a spanner slips and damages the corners of a fastener.

M6 Bolt Maximum Torque Thresholds

The standard for different bolt sizes and grades is high. Thus, we ensure our tools could handle the weight and the torque needed to tighten your bolts.

Do note that you should only follow the setting shown in the table unless the machine manufacturer has specified otherwise.

Thread is produced by different processes and in various finishes to meet specific needs

The power of the threaded connection is the weakest point. So, if you’re applying torque, make sure it’s screwed into a harder material like aluminum or steel.

If you’re trying to make a thread from a piece of metal, the size of the drilled hole may vary based on how the drill is sharpened and used.

Now you can get a perfect fit every time! The hole might not be precisely straight, and if it’s blunt or worn out, it won’t fit as it should.

Design Engineers must consider all of these factors and may decide that a lower torque is applicable. This is the case in lifting devices where high aspects of safety are required.

M6 Standard Proof Loads

When you’re trying to decide how much load a bolt should carry, it’s important to understand the “proof load.” The standard for this is typically around 90% of the load the bolt begins to stretch.

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In manufacturer’s tables, proof loads are usually given in Newtons, but in this table, we’ve converted them into kg force. The proof load is the maximum load a bolt can carry.

In other terms, the proof load is an applied tensile load that the bolt must support without permanent damage.

To ensure that the bolt returns to its original shape once the load is removed. Manufacturers design their machines so the bolts bear less than the proof load for a good safety factor.

Frequently Asked Questions (FAQs):

What Do Bolt Sizes Mean?

So you need metric bolts, but you don’t know how to read them? No problem! Metric bolts can be measured using the “M” s. In M8-1.0*20, the “M” means the Metric thread designation. Number eight refers to the Nominal diameter (in millimeters), 1.0 refers to its length.

Is M6 Bolt Bigger Than M8?

Yes, It is. Metric threads are designated by the number of threads per inch and diameter. The most common metric threading is M6, which has an ISO dimension of 6 x 1 mm.

5mm Allen wrenches or 9/10mm hexagonal wrenches can unscrew nuts and bolts with metric threading.

As for M8 bolts, you can find them on the 8mm diameter, but they’re also used in other pitches.

They have an ISO dimension of M8 x 1.25mm. Moreover, you can also use Allen wrenches or hexagonal wrenches to screw or unscrew them.

When should I use fine thread nuts/bolts?

When working with metal, you will need to use fine threaded bolts. For example, when attaching a metal piece to another piece of metal.

Or in the case of fastening a washer and nut together with a threaded bolt.

What Is Bolt Thread Size?

Metric fasteners are different. They use a thread pitch instead of a thread count, the distance between threads expressed in millimeters.

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Thread pitch refers to the distance between one thread and the next, and small fasteners have a finer line. A smaller number is actually better, so we use a lower number for our fasteners.

What Is Equivalent To M6?

Based on this table, M8 bolts are a near equivalent of M6 bolts. Though they might work together in some cases, usually they are not compatible with each other.

Using incompatible bolts might cause faults in machinery when ignored.

Precise Use of M6 Bolts

This article covers the usage of M6 bolts and their size and specifications. Complete with the important details about M6 bolts, Avoid complications in your project!

Feel free to visit this article anytime for a project that requires you to use M6 bolts. Use this as a guide for you to have instructions to look at whenever you’re confused with something.

Remember to keep this guide close to you for future use.

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