Foreword

ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.

The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).

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This document was prepared by Technical Committee ISO/TC 1, Screw threads.

This fifth edition cancels and replaces the fourth edition ( ISO 965-1:2013 ), which has been technically revised. It also incorporates the Amendment ISO 965-1:2013/Amd.1:2021 .

The main changes are as follows:

in Clauses 6, 7 and A.1, the last paragraphs (special tolerances) have been added;
Clause 10 and Clause 13.5 have been added;
Annex B has been added, and the symbol T_d3 has been added in Clause 4.

A list of all parts in the ISO 965 series can be found on the ISO website.

Any feedback or questions on this document should be directed to the user’s national standards body. A complete listing of these bodies can be found at www.iso.org/members.html .

1 Scope

This document specifies a tolerance system for ISO general purpose metric screw threads (M) conforming to ISO 261 having basic and design profiles in accordance with ISO 68-1 .

2 Normative references

3 Terms and definitions

4 Symbols

5 Tolerance system

6 Tolerance positions

7 Tolerance grades

8 Length groups of thread engagement

9 Recommended tolerance classes

9.1 General

9.2 Tolerance quality

9.3 Preference order

9.4 Combination of internal and external threads

10 Coated threads

11 Multiple-start threads

12 Root contours and truncations

12.1 General

12.2 Internal threads

12.3 External threads

13 Designation

13.1 General

13.2 Designation of single-start threads

13.3 Designation of multiple-start threads

13.4 Designation of left-hand threads

13.5 Designation of coated threads

Bibliography

ISO 965-1:2026

ISO general purpose metric screw threads. Tolerances — - Part 1: Principles and basic data

Current

Published:

14 Apr 2026

1 Scope