DIN ISO 965-1:2026-09

What is DIN ISO 965-1 about?

DIN ISO 965-1 specifies the tolerance system for ISO metric screw threads and describes the basic rules for tolerances, tolerance classes and tolerance positions for internal and external threads. It forms the basis for the uniform design and inspection of ISO threads and supports the interchangeability and functional reliability of fasteners.

The standard applies to ISO metric screw threads for general use in accordance with ISO 261, with basic and nominal profiles in accordance with ISO 68-1, and defines the fundamentals for fits, thread tolerances and lengths of thread engagement.

What content does the standard cover?

DIN ISO 965-1 describes the tolerance system for internal and external threads and provides specifications for selecting suitable tolerance classes for different applications. It also covers coated threads, multiple-start threads and thread designations.

Topics covered at a glance:

• Tolerance system for ISO metric screw threads
• Tolerance positions and tolerance grades for internal and external threads
• Thread fits and recommended tolerance classes
• Thread engagement groups and lengths of thread engagement
• Coated threads and thread tolerances after coating
• Multiple-start threads
• Contour and design of the thread root
• Thread designation and specification

Why is the standard relevant in practice?

DIN ISO 965-1 creates a uniform basis for the design and manufacture of ISO metric screw threads. It supports manufacturers, designers and quality managers in defining suitable thread tolerances, tolerance classes and thread fits.

The specifications for selecting internal and external threads, matching threaded components and handling coated threads are particularly relevant. As a result, the standard contributes to the functional reliability, interchangeability and quality of fasteners.

What changes have been made compared with the previous edition?

Compared with DIN ISO 965-1:2017-05, the standard has been comprehensively revised. The most important changes include:

• Extension of the scope to ISO metric screw threads in accordance with ISO 261 and ISO 68-1
• Inclusion of tolerances for the minor diameter of external threads, including new calculation formulae
• Addition of specifications for special tolerances and special pitches
• New requirements for selecting tolerance classes for coated threads
• Inclusion of rules for the designation of coated threads
• Expanded specifications for the contour of the thread root
• Revision and restructuring of the calculation formulae
• Consideration of ISO 965-1:2013/Amd.1:2021
• Adjustment of terminology, in particular the change from “Steigung” to “Teilung” for the symbol P

Target audience

• Manufacturers of fasteners
• Designers and development engineers
• Threading and fastening technology specialists
• Quality managers and inspection bodies
• Tool manufacturers
• Companies in mechanical engineering, automotive engineering and metalworking

Conclusion

DIN ISO 965-1 is the fundamental standard for thread tolerances and thread fits for ISO metric screw threads. It defines the principles of the tolerance system and supports the standards-compliant design, manufacture and inspection of internal and external threads. With its recent extensions regarding coated threads, minor diameters and calculation methods, it provides an important basis for modern fastening technology.

This document replaces DIN ISO 965-1:2017-05 .