General Purpose Screw Threads

These standards from ISO and SAE cover Standardized Threading for Screws and Bolts requirements sorted by threading. This list covers general purpose screw standards.

ISO 68-1:2023

ISO general purpose screw threads - Basic and design profiles - Part 1: Metric screw threads

This document specifies the basic and design profiles for ISO general purpose metric screw threads (M). This document is applicable to the metric fastening screw threads.

ISO 68-2:2023

ISO general purpose screw threads - Basic and design profiles - Part 2: Inch screw threads

This document specifies the basic and design profiles for ISO inch screw threads (UN and UNR). UN applies to both internal and external threads. UNR only applies to external threads. A flat or rounded root contour, due to the threading process, is specified for UN threads, while only a defined rounded root contour is specified for UNR external threads. This document is applicable to the inch fastening screw threads.

ISO 724:2023

ISO general purpose metric screw threads - Basic dimensions

This document specifies the basic dimensions of ISO general purpose metric screw threads according to ISO 261 . The values refer to the design profiles according to ISO 68 - 1 . This document is applicable to the metric fastening screw threads.

ISO 1502:1996

ISO general-purpose metric screw threads - Gauges and gauging

Gives details for the manufacture and use of gauges for checking ISO general purpose metric screw threads. Specifies the features of gauges which are recommended for checking external and internal screw threads of workpieces. Provides means of distinguishing between threads that comply with the limits of size and those that do not.

ISO 261:1998

ISO general-purpose metric screw threads - General plan

This International Standard specifies ISO general purpose metric screw threads (M) having basic profile according to ISO 68-1. Basic dimensions are given in ISO 724. For tolerances see ISO 965-1.

ISO 262:2023

ISO general purpose metric screw threads - Selected sizes for bolts, screws, studs and nuts

This document specifies the selected sizes for bolts, screws, studs and nuts in the diameter range from 1 mm to 100 mm of ISO general purpose metric screw threads (M) having the basic and design profiles according to ISO 68 - 1 . These sizes of diameter and pitch combinations are selected from ISO 261 . This document is applicable to the metric commercial fastener screw threads.

ISO 885:2000

General purpose bolts and screws - Metric series - Radii under the head

This International Standard specifies the sizes of the radii under the head and the transition diameters of metric series general purpose bolts and screws.

ISO 965-2:2024

ISO general purpose metric screw threads - Tolerances - Part 2: Limits of sizes for internal and external threads (tolerance classes 6H and 6g for M1,6 to M100 and 5H and 6h for M1 to M1,4)

This document specifies the limits of sizes for pitch and crest diameters of ISO general purpose metric screw threads (M) conforming to ISO 262 having basic and design profiles according to ISO 68-1. This document is applicable to the metric fastening screw threads with tolerance classes 6H and 6g for M1,6 to M100 and 5H and 6h for M1 to M1,4.

ISO 965-3:2021

ISO general purpose metric screw threads - Tolerances - Part 3: Limit deviations for screw threads

This document specifies limit deviations for pitch and crest diameters for ISO general purpose metric screw threads (M) conforming to ISO 261 having basic profile in accordance with ISO 68-1. The limit deviations specified are derived from the fundamental deviations and tolerances specified in ISO 965-1. This document is applicable to ISO general purpose metric screw threads with the recommended tolerance classes.

ISO 965-4:2025

ISO general purpose metric screw threads - Tolerances - Part 4: Limits of sizes for hot-dip galvanized external threads to mate with internal threads made to tolerance position H or G after galvanizing

This document specifies the fundamental deviations and limits of sizes for the pitch and major diameters of the hot-dip galvanized metric external threads (M) conforming to ISO 262 (M6 to M68 with the coarse pitches and M72 to M100 with pitch 6) having basic and design profiles in accordance with ISO 68-1. This document is applicable to the hot-dip galvanized metric external threads undersized to tolerance class 6az before galvanizing to mate with the internal threads made to tolerance position H or G after galvanizing.

ISO 965-5:2025

ISO general purpose metric screw threads - Tolerances - Part 5: Limits of sizes for internal threads to mate with hot-dip galvanized external threads with maximum size of tolerance position h before galvanizing

This document specifies the fundamental deviations and limits of sizes for the pitch and minor diameters of ISO general purpose metric internal threads (M) conforming to ISO 262 (M6 to M68 with the coarse pitches and M72 to M100 with pitch 6) having basic and design profiles in accordance with ISO 68-1. This document is applicable to the metric internal threads oversized to tolerance class 6AZ or 6AX to mate with the hot-dip galvanized external threads with maximum size of tolerance position h before galvanizing. This document is not applicable to internal threads with coating on thread surface. The limits of sizes before coating are decided by agreement between manufacturer and purchaser.