Reference Chart

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.

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

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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	K	L
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.

Frequently Asked Questions

What is ISO 2768 and when should I use it?

ISO 2768 is a standard for general tolerances. It applies to linear and angular dimensions on machined parts. Use it when a drawing does not show a specific tolerance for a feature. It saves time by removing the need to add tolerances to every single dimension.

What is the difference between ISO 2768-1 and ISO 2768-2?

ISO 2768-1 covers linear and angular dimensions. It sets the allowed variation for lengths, widths, heights, and angles. ISO 2768-2 covers geometric tolerances like straightness, flatness, perpendicularity, and symmetry. A drawing often calls out both, such as ISO 2768-mK.

What does ISO 2768-mK mean on a drawing?

The lowercase letter is the linear tolerance class from ISO 2768-1. The uppercase letter is the geometric tolerance class from ISO 2768-2. So ISO 2768-mK means medium linear tolerances and K-class geometric tolerances. This is the most common callout for general machined parts.

Which ISO 2768 tolerance class should I pick for CNC machined parts?

For most CNC machined parts, class m (medium) works well. It matches what a good CNC machine can hold without extra effort. Use class f (fine) for tighter features. Use class c (coarse) for parts where fit is not critical, like covers or brackets.

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ISO 2768 Tolerance Chart

ISO 2768-1 Linear Tolerances

ISO 2768-1 Angular Tolerances

ISO 2768-2 Geometric Tolerances

Straightness & Flatness

Perpendicularity

Symmetry

Tolerance Lookup Tool

When to Use Each Tolerance Class

Frequently Asked Questions

More Resources

Get Your Parts Made Right

ISO 2768 Tolerance Chart

ISO 2768-1 Linear Tolerances

ISO 2768-1 Angular Tolerances

ISO 2768-2 Geometric Tolerances

Straightness & Flatness

Perpendicularity

Symmetry

Tolerance Lookup Tool

When to Use Each Tolerance Class

Frequently Asked Questions

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