Whitworth thread – chart, dimensions, applications

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What is a Whitworth thread?

Whitworth thread is the British national thread type developed in 1841 by Joseph Whitworth.

Prior to that, there were no generally accepted standards. Each company had its own standards, which led to a lot of confusion.

Whitworth threads were the answer to this difficulty, and the fact that we still use them today is testament to the effectiveness of such standardisation.

What are the designations of Whitworth thread?

Here are the most common designations of the Whitworth thread:

  • BSW (British standard Whitworth) - plain Whitworth inch thread, cylindrical; 
  • BSF (British Standard Fine) - Whitworth inch thread, fine thread; 
  • BSPP (British Standard Pipe Parallel) - Whitworth pipe thread, cylindrical; 
  • BSPT (British Standard Pipe Taper) - Whitworth pipe thread, tapered.

The Whitworth thread standard is described by specific abbreviations that you will find on today's construction parts.

Whitworth Thread Scheme

What is the difference between Whitworth pipe threads and Whitworth inch threads?

The main difference between Whitworth pipe thread and Whitworth inch thread is the difference in their standards and dimensions. Many people make the mistake of distinguishing between Whitworth threads. Thus, they pick the wrong thread sizes when using charts with standards.

What are the dimensions of Whitworth thread? Whitworth threads chart

Below you will find separate charts for Whitworth pipe and inch threads.

Whitworth inch threads chart

Thread Number of coils per inch Hole Ø [mm] Platen Ø [mm]
BSW 1/8 40 2.55 3.09
BSW 3/16 24 3.7 4.66
BSF 3/16 32 4 4.76
BSW 1/4 20 5.1 6.24
BSF 1/4 26 5.3 6.25
BSW 5/16 18 6.5 7.82
BSF 5/16 22 6.8 7.83
BSW 3/8 16 7.9 9.4
BSF 3/8 20 8.3 9.41
BSW 7/16 14 9.25 10.98
BSF 7/16 18 9.7 10.99
BSW 1/2 12 10.5 12.56
BSF 1/2 16 11.1 12.57
BSW 9/16 12 12 14.14
BSF 9/16 16 12.7 14.16
BSW 5/8 11 13.5 15.72
BSF 5/8 14 14 15.73
BSW 3/4 10 16.4 18.89
BSF 3/4 12 16.75 18.89
BSW 7/8 9 19.25 22.1
BSF 7/8 11 19.75 22.11
BSW 1 8 22 25.27
BSF 1 10 22.75 25.28
BSW 1-1/8 7 24.75  
BSW 1-1/4 7 27.75  
BSW 1-1/2 6 33.5  
BSW 1-3/4 5 39  
BSW 2 4.5 44.5  

Whitworth pipe thread chart

Thread size [inch] Number of coils per inch Thread pitch in [mm] Outer Diameter [mm] Inner Diameter [mm]
1/8 28 0.907 9.728 8.565
1/4 19 1.337 13.157 11.445
3/8 19 1.337 16.662 14.95
1/2 14 1.814 20.955 18.633
3/4 14 1.814 26.441 24.12
1 11 2.309 33.249 30.292
1 1/4 11 2.309 41.91 38.953
1 1/2 11 2.309 47.803 44.846
2 11 2.309 59.614 56.657
2 1/2 11 2.309 75.184 72.227
3 11 2.309 87.884 84.927
4 11 2.309 113.03 110.073

What is the application of Whitworth thread?

Whitworth thread is used in military and multiple different types of machinery. As for the traditional BSW thread, it was first used on Royal Navy gunboats. And the more modern (due to its smaller pitch and depth) BSF thread was used in precision machinery and installations.

However, nowadays, inch threads in Europe are mainly used for the mechanical connection of hydraulic and gas installations, which is where you will encounter them most often, as they have become the standard in these industries.

Photo of Bartosz Kułakowski - CEO of Hosetech sp. z o. o.

Articles author

Bartosz Kułakowski

CEO of Hosetech Sp. z o.o.

Bartosz Kulakowski is an industrial hoses and couplings specialist with over 10 years of experience. Bartosz has been present in the technical industry since 2013. He gained experience as a technical and commercial advisor in the sector of plastic conveyor belts, steel structures, industrial hoses, and connectors. Since 2016, he has specialized exclusively in hoses and connectors. In 2019 he opened his own business under the HOSETECH Bartosz Kulakowski brand and since July 2022 he has been the CEO of the capital company HOSETECH Sp z o. o. (LLC).

SPIS TREŚCI

What is a Whitworth thread?

What are the designations of Whitworth thread?

What is the difference between Whitworth pipe threads and Whitworth inch threads?

What are the dimensions of Whitworth thread? Whitworth threads chart

Whitworth inch threads chart

Whitworth pipe thread chart

What is the application of Whitworth thread?

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