ISO 2768 Tolerance Chart
ISO 2768 sets general tolerances for machined parts. It covers linear sizes, angles, and part shape. Use this chart when a drawing does not list a specific tolerance. Pick a class, find your size range, and read the allowed variation.
Quick Answer: What Is ISO 2768?
ISO 2768 is the international standard for general tolerances. It applies to linear sizes, angles and geometric features that have no individual tolerance called out on the drawing. ISO 2768-1 covers linear and angular dimensions in four classes (f fine, m medium, c coarse and v very coarse), and ISO 2768-2 covers geometric tolerances in three classes (H, K and L).
A callout like ISO 2768-mK means medium linear plus K-class geometric.
This chart lists ISO 2768 tolerance values in millimeters for: linear dimensions by nominal size range, angular dimensions by shorter-side length and geometric tolerances for straightness, flatness, perpendicularity and symmetry. Inputs are the nominal dimension and the tolerance class. The lookup tool returns the exact ± value from ISO 2768-1.
Common values (class m, medium): 0.5–3 mm → ±0.1 mm | 6–30 mm → ±0.2 mm | 30–120 mm → ±0.3 mm | 120–400 mm → ±0.5 mm | angular up to 10 mm → ±1° | geometric flatness 30–100 mm, K class → 0.2 mm.
ISO 2768-1 Linear Tolerances
These are the allowed deviations for linear dimensions like length, width, height, and diameter. All values are in millimeters. A dash means that class does not apply for that range.
| NOMINAL RANGE (MM) | F-FINE | M-MEDIUM | C-COARSE | V- VERY COARSE |
| 0.5 – 3 | ±0.05 | ±0.1 | ±0.2 | — |
| 3 – 6 | ±0.05 | ±0.1 | ±0.3 | ±0.5 |
| 6 – 30 | ±0.1 | ±0.2 | ±0.5 | ±1.0 |
| 30 – 120 | ±0.15 | ±0.3 | ±0.8 | ±1.5 |
| 120 – 400 | ±0.2 | ±0.5 | ±1.2 | ±2.5 |
| 400 – 1000 | ±0.3 | ±0.8 | ±2.0 | ±4.0 |
| 1000 – 2000 | ±0.5 | ±1.2 | ±3.0 | ±6.0 |
| 2000 – 4000 | — | ±2.0 | ±4.0 | ±8.0 |
ISO 2768-1 Angular Tolerances
These are the allowed deviations for angular dimensions. The shorter side of the angle sets which range to use. Values are shown in degrees and minutes of arc.
| NOMINAL LENGTH (MM) | F-FINE | M-MEDIUM | C- COARSE | V- VERY COARSE |
| Up to 10 | ±1° | ±1° | ±1°30′ | ±3° |
| 10 – 50 | ±0°30′ | ±0°30′ | ±1° | ±2° |
| 50 – 120 | ±0°20′ | ±0°20′ | ±0°30′ | ±1° |
| 120 – 400 | ±0°10′ | ±0°10′ | ±0°15′ | ±0°30′ |
| Over 400 | ±0°5′ | ±0°5′ | ±0°10′ | ±0°20′ |
ISO 2768-2 Geometric Tolerances
These tolerances control the shape and position of features. They apply when a drawing calls out ISO 2768-2. The uppercase letter (H, K, or L) sets the class. All values are in millimeters.
Straightness & Flatness
| NOMINAL RANGE (MM) | H | K | L |
| Up to 10 | 0.02 | 0.05 | 0.1 |
| 10 – 30 | 0.05 | 0.1 | 0.2 |
| 30 – 100 | 0.1 | 0.2 | 0.4 |
| 100 – 300 | 0.2 | 0.4 | 0.8 |
| 300 – 1000 | 0.3 | 0.6 | 1.2 |
| 1000 – 3000 | 0.5 | 1.0 | 2.0 |
Perpendicularity
| NOMINAL RANGE (MM) | H | L | K |
| Up to 100 | 0.2 | 0.4 | 0.6 |
| 100 – 300 | 0.3 | 0.6 | 1.0 |
| 300 – 1000 | 0.4 | 0.8 | 1.5 |
| 1000 – 3000 | 0.5 | 1.0 | 2.0 |
Symmetry
| NOMINAL RANGE (MM) | H | K | L |
| Up to 100 | 0.5 | 0.6 | 0.6 |
| 100 – 300 | 0.5 | 0.6 | 1.0 |
| 300 – 1000 | 0.5 | 0.8 | 1.5 |
| 1000 – 3000 | 0.5 | 1.0 | 2.0 |
When to Use Each Tolerance Class
- Class f (Fine)— Use for tight fits and precision parts. Good for bearing bores, mating surfaces, and high-accuracy assemblies. Needs careful CNC work.
- Class m (Medium)— The most common class. Works well for general CNC machined parts. Most shops can hold these tolerances without extra effort.
- Class c (Coarse)— Use for parts where fit is not critical. Good for covers, brackets, and non-mating features. Keeps cost low.
- Class v (Very Coarse)— Use for rough parts, castings, or flame-cut pieces. Not common for CNC work. Only applies to larger sizes.
- A drawing note like “ISO 2768-mK” means linear class m and geometric class K. This is the most common callout for machined parts.
- A dash (—) in the table means that class does not apply for that size range.
- These are general tolerances. They only apply to features that do not have a specific tolerance called out on the drawing.
Need Parts Machined to ISO 2768 General Tolerances?
We machine custom components to ISO 2768-f, -m, and -c specifications. Every order receives a comprehensive, complimentary DFM review to ensure drawings and tolerance standards align with the manufacturing process.
Frequently Asked Questions
What is ISO 2768 and when should I use it?
ISO 2768 defines general tolerances for machined parts, covering unspecified linear and angular dimensions. It is useful when individual features do not have their own tolerance values, reducing the need to specify a tolerance for every dimension on a drawing.
What is the difference between ISO 2768-1 and ISO 2768-2?
ISO 2768-1 establishes general tolerances for linear and angular dimensions, including lengths, widths, heights, and angles. ISO 2768-2 addresses general geometric tolerances such as straightness, flatness, perpendicularity, and symmetry. A drawing may reference both standards together, for example, as ISO 2768-mK.
What does ISO 2768-mK mean on a drawing?
In ISO 2768-mK, the lowercase m identifies the linear and angular tolerance class under ISO 2768-1, while the uppercase K specifies the geometric tolerance class under ISO 2768-2. This combination indicates medium general dimensional tolerances with K-class geometric tolerances and is commonly used for general machined parts.
Which ISO 2768 tolerance class should I use for CNC machined parts?
Class m (medium) is suitable for many general CNC machined parts and provides a practical balance between accuracy and machining cost. Choose f (fine) when tighter general tolerances are required, while c (coarse) can be appropriate for non-critical features such as covers and brackets.
