General Tolerances for Linear and Angular Dimensions – ISO 2768 Tolerance Chart

General Tolerances for Linear and Angular Dimensions – ISO 2768 Tolerance Chart

In today’s technical world, precise measurements matter. That’s where the ISO 2768 Tolerance Chart comes into play. Why should you care? For starters, industries around the globe rely on ISO 2768.

From building skyscrapers to crafting intricate machinery, precise tolerances ensure safety and quality. By the end of this article, you’ll grasp why these standards are pivotal. Plus, you’ll discover which tolerance suits your needs best.

What is ISO 2768?

ISO 2768 is not just any standard. It’s a globally accepted framework that sets general tolerances for linear and angular dimensions. But what does that mean?

Linear dimensions refer to measurements in a straight line. Think of the length, width, or height of an object. Angular dimensions, on the other hand, deal with angles. It could be the bend in a metal sheet or the tilt of a machine part.

In the manufacturing world, accuracy is vital. Small errors can lead to big problems. ISO 2768 ensures that products and parts meet specific tolerances. These tolerances set the allowable range for measurements. In simpler terms, it’s the wiggle room a measurement can have and still be acceptable.

For instance, if a machine part needs to be 10 cm long, ISO 2768 might say it can be 10.05 cm or 9.95 cm, but no more or less. This small range guarantees safety, functionality, and consistency.

Manufacturers, engineers, and designers across industries turn to ISO 2768. It offers a clear path to maintain quality. When everyone follows the same standard, we see fewer errors and more harmony in production.

Read More: Surface Roughness Chart: Understanding Surface Finish in Manufacturing

What Does ISO 2768-mK Mean?

Diving deeper into ISO 2768, you might come across terms like “mK” and wonder about their significance. Don’t fret; we’re here to demystify it.

“m” in ISO 2768-mK stands for “medium”. This represents a specific level of tolerance. There are various tolerance levels in ISO 2768, such as ‘f’ for fine, ‘c’ for coarse, and ‘v’ for very coarse. Each level dictates how much deviation is acceptable from the intended measurement.

Now, what about that “K”? It signifies geometrical tolerances. In simpler terms, it’s about the shape and placement of an object. Imagine a metal rod; its straightness or how centred it is are factors determined by geometrical tolerances.

Combine the two – “m” and “K” – and get a clear picture. ISO 2768-mK provides guidelines for medium-level measurement deviations, considering both the size and shape.

This distinction is essential in industries where precision is key. Take aerospace, for instance. In building aircraft, parts need to fit together flawlessly.

A slight misalignment or incorrect size can compromise the entire structure. By adhering to ISO 2768-mK, manufacturers can ensure that each part aligns perfectly, maintaining the plane’s integrity.

ISO 2768-mK is a specific subset of the broader ISO 2768 standard. It zeroes in on medium tolerances with an emphasis on geometrical aspects; for professionals in fields where every millimetre counts, understanding and applying this standard can be the difference between success and costly errors.

Check Out: Surface Roughness Chart: Ra and Rz Roughness Specification

Which Tolerance to Choose?

Which Tolerance to Choose?

Navigating the world of ISO tolerances might seem intricate, but understanding the nuances can streamline your decisions. Different projects and products require specific tolerances, and this is where ISO 2768-1 and ISO 2768-2 come into play.

Part 1: General Tolerances for ISO 2768-1

ISO 2768-1 focuses on general tolerances for linear and angular dimensions without individual tolerance indications. This standard is the go-to when you’re dealing with products that don’t need specific tolerance indications.

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
0.5 up to 3± 0.05± 0.1± 0.2
over 3 up to 6± 0.05± 0.1± 0.3± 0.5
over 6 up to 30± 0.1± 0.2± 0.5± 1
over 30 up to 120± 0.15± 0.3± 0.8± 1.5
over 120 up to 400± 0.2± 0.5± 1.2± 2.5
over 400 up to 1000± 0.3± 0.8± 2.0± 4.0
over 1000 up to 2000± 0.5± 1.2± 3.0± 6.0
over 2000 up to 4000± 2.0± 4.0± 8.0
Table 1. Linear Dimension (General Tolerance Chart- 1)

Permissible deviations in mm for ranges in nominal lengths
Tolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
0.5 up to 3± 0.2± 0.2± 0.4± 0.4
over 3 up to 6± 0.5± 0.5± 1.0± 1.0
over 6± 1.0± 1.0± 2.0± 2.0
Table 2. External Radii and Chamfer Heights (General Tolerance Chart- 2)

Permissible deviations in mm for ranges in nominal lengthsTolerance Class Designation (Description)
f (fine)m (medium)c (coarse)v (very coarse)
up to 10± 1º± 1º± 1º30/
over 10 up to 50± 0º30/± 0º30/± 1º± 2º
over 50 up to 120± 0º20/± 0º20/± 0º30/± 1º
over 120 up to 400± 0º10/± 0º10/± 0º20/± 0º30/
over 400± 0º5/± 0º5/± 0º10/± 0º20/
Table 3. Angular Dimensions (General Tolerance Chart- 3)

Depending on the Nature of the Work:

  • Consider the ‘f’ (fine) tolerance for very precise parts.
  • ‘m’ (medium) tolerance is often the middle ground, suitable for most general applications.
  • When the exact size isn’t crucial, ‘c’ (coarse) or ‘v’ (very coarse) might be apt.

Each category has its own set of tolerances for different length ranges. Matching your needs with the right tolerance range is essential to ensure optimal performance and fit.

Part 2: General Tolerances for ISO 2768-2

ISO 2768-2 is a tad different. This standard zeroes in on general tolerances for geometrical quantities, essentially parts’ shape and relative position.

Ranges of nominal lengths in mmTolerance Class
up to
above 10 to 300.050.10.2
above 30 to 1000.10.20.4
above 100 to 3000.20.40.8
above 300 to 10000.30.61.2
above 1000 to 30000.40.81.4
Table 4. General Tolerances on Straightness and Flatness

Ranges of nominal lengths in mmTolerance Class
up to
above 10 to 300.30.61.0
above 30 to 1000.40.81.5
above 100 to 3000.51.02.0
Table 5. General Tolerances on Perpendicularity

Ranges of nominal lengths in mmTolerance Class
up to
above 10 to 300.50.61.0
above 30 to 1000.50.81.5
above 100 to 3000.51.02.0
Table 6. General Tolerances on Symmetry

While ISO 2768-1 gives you wiggle room in length or angle, ISO 2768-2 ensures that the produced part will fit perfectly in its intended position. Factors like Straightness, perpendicularity, and symmetry fall under this.

When deciding between the two, it’s essential to evaluate:

  • The exactness required in your product’s dimensions.
  • The necessity of maintaining geometric relationships between parts.

In many cases, both standards may be utilized in tandem. For example, a car engine part might need the strict linear dimensions from ISO 2768-1 and the geometric consistency from ISO 2768-2.

Read Out: GD&T 101: An Introduction to Geometric Dimensioning and Tolerancing


In the vast manufacturing realm, ISO 2768 is a beacon guiding precision and quality. As intricate as they seem, these tolerance charts serve as a blueprint for consistency and safety.

As you delve into projects, ask yourself: Which standard aligns best with my needs? And, could the right choice significantly elevate product integrity? Remember, the nuances in these standards can make or break the functionality and success of an end product.

Kemal Manufacturing stands as a testament to this principle. By adhering strictly to these standards, we exemplify the pinnacle of precision in our products.

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