Thread type: BSF - Britsh Standard Fine Whitworth BS 84

British Whitworth fine thread

The thread that we present to you in the BSF thread table is the British Standard Fine thread. The values in the BSF thread table correspond to the BS 84 standard, which is part of the British Standards and is subject to monitoring by the British Standards Institution (BSI). The BSF thread is the alternative to the BSW standard thread in cases where a higher number of threads per inch is required.Although the BSF thread, like the British standard thread, is often given the suffix Whitworth, the values defined in the BSF thread table are not a thread standard defined by the British engineer Joseph Whitworth. In fact, the BSF thread was not created until a good 60 years later and was first introduced by the British Engineering Standards Association in 1908. Nevertheless, it is based on the British Whitworth standard thread and is therefore closely related to it.

The thread from our BSF thread table has a flank angle of 55°, all dimensions are in inches. It was once widely used in British industry and was used for machine tools as well as numerous components of iconic British car brands. However, the BSF thread was increasingly displaced first by the American fine pitch thread UNF and later also by the metric fine pitch thread and now only plays a minor role.

In the table for the BSF thread you will find thread sizes from 3/16" up to 4".These are each designated with a combination of the abbreviation BSF and the outside diameter. The information is given in inches as standard, but we also provide metric conversions to make it easier for you to work with the BSF thread table. This allows you to read the outside diameter in mm from the table. The BSF thread table also has a conversion of the usual information on threads per inch for inch threads into a pitch value in mm.

 Major Diameter inchMajor Diameter mmTPIPitch P in mm
BSF 3/16"0,1884,76332,0000,794
BSF 7/32"0,2195,55628,0000,907
BSF 1/4"0,2506,35026,0000,977
BSF 9/32"0,2817,14226,0000,977
BSF 5/16"0,3137,93822,0001,154
BSF 3/8"0,3759,52520,0001,270
BSF 7/16"0,43811,11318,0001,411
BSF 1/2"0,50012,70016,0001,587
BSF 9/16"0,56314,28816,0001,587
BSF 5/8"0,62515,87514,0001,814
BSF 11/16"0,68817,46314,0001,814
BSF 3/4"0,75019,05012,0002,117
BSF 7/8"0,87522,22511,0002,309
BSF 1"1,00025,40010,0002,540
BSF 1 1/8"1,12528,5759,0002,822
BSF 1 1/4"1,25031,7509,0002,822
BSF 1 3/8"1,37534,9258,0003,175
BSF 1 1/2"1,50038,1008,0003,175
BSF 1 5/8"1,62541,2758,0003,175
BSF 1 3/4"1,75044,4507,0003,628
BSF 2"2,00050,8007,0003,628
BSF 2 1/4"2,25057,1506,0004,233
BSF 2 1/2"2,50063,5006,0004,233
BSF 2 3/4"2,75069,8506,0004,233
BSF 3"3,00076,2005,0005,080
BSF 3 1/4"3,25082,5505,0005,080
BSF 3 1/2"3,50088,9004,5005,644
BSF 3 3/4"3,75095,2504,5005,644
BSF 4"4,000101,6004,5005,644
Cross section of a BSF thread