Screw threads

Screw thread standards are amongst the oldest published by BSI British Standards. Standards for machine screw threads have evolved since the early nineteenth century to facilitate compatibility between different manufacturers and users.

Although there are sometimes 50 years between revisions, the longevity of these designs highlight the need for updated standards. A crucial element in manufacturing and engineering, the newly updated standards will be relevant for many years to come.

BSI British Standards offers a wide range of standards which are essential for anyone involved in manufacturing screw threads.

Key standards


Browse all screw threads products and standards

BS 1580 Unified Screw threads series

BS 1580-1:2007
Unified screw threads. Screw threads with diameters ¼ in and larger. Requirements

BS 1580-3:2007
Unified screw threads. Screw threads with diameters below ¼ in. Requirements

BS 919 Screw gauge limits and tolerances series

BS 919-1:2007
Specification for screw gauge limits and tolerances. Gauges for screw threads of unified form

BS 919-2:2007
Specification for screw gauge limits and tolerances. Gauges for screw threads of Whitworth and BA forms

BS 919-3:2007
Screw gauge limits and tolerances. Specification for gauges for screw threads of ISO metric form

BS 919-4:2007
Specification for screw gauge limits and tolerances. Limits for size for gauges of screw threads of unified form diameters 1/4 in and larger

BS 3643 ISO metric screw threads series

BS 3643-1:2007
ISO metric screw threads. Principles and basic data

BS 3643-2:2007
ISO metric screw threads. Specification for selected limits of size

Other standards

BS 84:2007
Parallel screw threads of Whitworth form. Requirements

BS 93:2008 
British Association (B.A.) screw threads. Requirements

BIP 2191:2011
BSI Handbook 44. Threaded Fasteners

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