Imperial Thread Forms and Pitch

Anzor Stainless Steel Fasteners & Fittings

Diameter (Inches)

 

Threads Per Inch (TPI)

BSW

UNC

UNF

BSF

1/8 40 40    
5/32 32 32    
3/16 24 24 32 32
1/4 20 20 28 26
5/16 18 18 24 22
3/8 16 16 24 20
7/16 14 14 20 18
1/2 12 13 20 16
5/8 11 11 18 14
3/4 10 10 16 12
7/8 9 9 14 11
1 8 8 12 10
1-1/8 7 7 12 9
1-1/4 7 7 12 9
1-1/2 6 6 12 8

UNC Thread Form P = Pitch = 1/Number of threads per inch (tpi) H = Angular Depth = 0.866025 x P H/8 = Shortening of major dia = 0.108253 x P H/4 = Shortening of minor dia = 0.216506 x P d = Actual Depth = 0.541266 x P r = Radius at the Root = 0.1443 x P Hn = Basic height of Internal Thread = 0.54127 x P Hs = Basic height of External Thread = 0.61344 x P BSW Thread Form P = Pitch = 1/Number of threads per inch (tpi) h = Angular Depth = 0.960491 x P D = Depth of Rounding = 0.073917 x P h/6 = Shortening = 0.160083 x P d = Actual Depth = 0.640327 x P r = Radius at the Crest & Root = 0.137329 x P C = Core diameter = Major Diameter - 1.280654 x P Effective or Pitch Diameter = Major Diameter - .640327 x P BSF Thread Form P = Pitch = 1/Number of threads per inch (tpi) h = Angular Depth = 0.960491 x P D = Depth of Rounding = 0.073917 x P h/6 = Shortening = 0.160083 x P d = Actual Depth = 0.640327 x P r = Radius at the Crest & Root = 0.137329 x P C = Core diameter = Major Diameter - 1.280654 x P Effective or Pitch Diameter = Major Diameter - .640327 x P BA Thread Form P = Pitch = 1/Number of threads per inch (tpi) h = Triangular height = 1.1363365 x P d = Actual Depth = 0.60000 x P t = Shortening = 0.2681688 x P r = Radius at the Crest & Root = 0.1808346 x P Effective or Pitch Diameter = Major Diameter - 0.6000 x P (d) C = Core diameter = Major Diameter - 1.2000 x P (2d) Nuts and Bolts across flats is nominally 1.75 x Major Diameter