MARYLAND METRICS
THREAD DATA CHARTS

BRITISH THREAD -- COARSE PITCH -- BSW

55 deg

Whitworth Coarse Thread BS 84
BSW (British Standard Whitworth)
British Standard Whitworth Coarse Thread Series (parallel, cylindrical)
In GB most common Thread. Corresponds to the Metric Thread in its type of use.
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MARYLAND METRICS -- THREAD DATA CHART:
British Thread (British Standard Whitworth) -- Coarse Pitch
Nominal
Size
Ww
Thread
Form
Type
Major
Diameter
mm
d=D
Pitch
mm
p
Threads
per
inch
tpi
Pitch
Diameter
mm
d2=D2
Minor
Diameter
Male Thd.
d3
Thread
Height
H1
Tap
Drill
Diameter
mm
1/16" BSW 1.587 0.423 60 1.315 1.050 0.270 1.15
3/32" BSW 2.381 0.529 48 2.041 1.703 0.338 1.90
1/8" BSW 3.175 0.635 40 2.768 2.362 0.406 2.50
5/32" BSW 3.969 0.793 32 3.459 2.952 0.507 3.20
3/16" BSW 4.762 1.058 24 4.084 3.407 0.677 3.70
7/32" BSW 5.556 1.058 24 4.878 4.201 0.677 4.50
1/4" BSW 6.350 1.270 20 5.537 4.724 0.813 5.10
5/16" BSW 7.938 1.411 18 7.034 6.131 0.904 6.50
3/8" BSW 9.525 1.588 16 8.509 7.492 1.017 7.90
7/16" BSW 11.113 1.814 14 9.951 8.789 1.162 9.20
1/2" BSW 12.700 2.117 12 11.345 9.990 1.355 10.40
9/16" BSW 14.290 2.117 12 12.930 11.580 1.355 11.89
5/8" BSW 15.876 2.309 11 14.397 12.918 1.479 13.40
3/4" BSW 19.051 2.540 10 17.424 15.798 1.627 16.25
7/8" BSW 22.226 2.822 9 20.419 18.611 1.807 19.25
1" BSW 25.400 3.175 8 23.368 21.335 2.033 22.00
1 1/8" BSW 28.576 3.629 7 26.253 23.929 2.324 24.50
1 1/4" BSW 31.751 3.629 7 29.428 27.104 2.324 27.25
1 3/8" BSW 34.926 4.233 6 32.215 29.505 2.711 30.25
1 1/2" BSW 38.100 4.233 6 35.391 32.680 2.711 33.50
1 5/8" BSW 41.277 5.080 5 38.024 34.771 3.253 35.50
1 3/4" BSW 44.452 5.080 5 41.199 37.946 3.253 38.50
1 7/8" BSW 47.627 5.645 4 1/2 44.012 40.398 3.614 41.25
2" BSW 50.802 5.645 4 1/2 47.187 43.573 3.614 44.50
2 1/4" BSW 57.152 6.350 4 53.086 49.020 4.066 50.00
2 1/2" BSW 63.502 6.350 4 59.436 55.370 4.066 56.00
2 3/4" BSW 69.853 7.257 3 1/2 65.205 60.558 4.647 61.50
3" BSW 76.203 7.257 3 1/2 71.556 66.909 4.647 68.00
3 1/4" BSW 82.553 7.816 3 1/4 77.548 72.544 5.005 73.75
3 1/2" BSW 88.903 7.816 3 1/4 83.899 78.894 5.005 80.00
3 3/4" BSW 95.254 8.467 3 89.832 84.410 5.422 85.50
4" BSW 101.604 8.467 3 96.182 90.760 5.422 92.00
4 1/4" BSW 107.954 8.835 2 7/8 102.297 96.639 5.657 98.00
4 1/2" BSW 114.304 8.835 2 7/8 108.647 102.990 5.657 104.20
4 3/4" BSW 120.665 9.237 2 3/4 114.740 108.625 5.915 110.00
5" BSW 127.005 9.237 2 3/4 121.090 115.176 5.915 116.50
5 1/4" BSW 133.355 9.677 2 5/8 127.159 120.963 6.196 122.50
5 1/2" BSW 139.705 9.677 2 5/8 133.509 127.313 6.196 128.50
5 3/4" BSW 146.055 10.160 2 1/2 139.549 133.043 6.506 134.50
6" BSW 152.406 10.160 2 1/2 145.900 139.394 6.506 141.00
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BRITISH THREAD -- FINE PITCH -- BSF

55 deg

Whitworth Fine Thread BS 84
British Standard Fine Thread Series (parallel, cylindrical)
BSW and BSF are the Thread selections for commercial screws and nuts.
This fine thread, which is widespread in the British machine tool industry,
is superseded by the American UNF Thread.

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MARYLAND METRICS -- THREAD DATA CHART:
British Thread (British Standard Fine) -- Fine Pitch
Nominal
Size
BSF
Thread
Form
Type
Major
Diameter
mm
d=D
Pitch
mm
p
Threads
per
inch
tpi
Pitch
Diameter
mm
d2=D2
Minor
Diameter
Male Thd.
d3
Thread
Height
H1
Tap
Drill
Diameter
mm
3/16" BSF 4.763 0.794 32 4.255 3.747 0.508 4.00
7/32" BSF 5.556 0.907 28 4.975 4.394 0.581 4.60
1/4" BSF 6.350 0.977 26 5.725 5.100 0.625 5.30
9/32" BSF 7.142 0.977 26 6.518 5.893 0.625 6.10
5/16" BSF 7.938 1.156 22 7.199 6.459 0.739 6.80
3/8" BSF 9.525 1.27 20 8.712 7.899 0.813 8.30
7/16" BSF 11.113 1.411 18 10.209 9.304 0.904 9.70
1/2" BSF 12.700 1.588 16 11.684 10.668 1.017 11.10
9/16" BSF 14.288 1.588 16 13.272 12.256 1.017 12.70
5/8" BSF 15.875 1.814 14 14.712 13.549 1.162 14.00
11/16" BSF 17.463 1.814 14 16.300 15.137 1.162 15.50
3/4" BSF 19.050 2.117 12 17.693 16.336 1.355 16.75
13/16" BSF 20.638 2.117 12 19.281 17.924 1.355 18.25
7/8" BSF 22.225 2.309 11 20.747 19.269 1.479 19.75
1" BSF 25.400 2.54 10 23.774 22.148 1.627 22.75
1 1/8" BSF 28.575 2.822 9 26.769 24.963 1.807 26.50
1 1/4" BSF 31.750 2.822 9 29.944 28.138 1.807 28.75
1 3/8" BSF 34.925 3.175 8 32.893 30.861 2.033 31.50
1 1/2" BSF 38.100 3.175 8 36.068 34.036 2.033 34.50
1 5/8" BSF 41.275 3.175 8 39.243 37.211 2.033 38.00
1 3/4" BSF 44.450 3.629 7 42.126 39.802 2.324 40.50
2" BSF 50.800 3.629 7 48.476 46.152 2.324 47.00
2 1/4" BSF 57.150 4.234 6 54.440 51.730 2.711 53.00
2 1/2" BSF 63.500 4.234 6 60.790 58.080 2.711 59.00
2 3/4" BSF 69.850 4.234 6 67.140 64.430 2.711 n/a
3" BSF 76.200 5.08 5 72.946 69.692 3.253 n/a
3 1/4" BSF 82.550 5.08 5 79.296 76.042 3.253 n/a
3 1/2" BSF 88.900 5.645 4 1/2 85.285 81.670 3.614 n/a
3 3/4" BSF 95.250 5.645 4 1/2 91.635 88.020 3.614 n/a
4" BSF 101.600 5.645 4 1/2 97.985 94.370 3.614 n/a
4 1/4" BSF 107.950 6.35 4 103.886 99.822 4.066 n/a

BSW & BSF thread notes:
C = Core diameter = Major Diameter - 1.280654 x P
d = Actual Depth = 0.640327 x P
D = Depth of Rounding = 0.073917 x P
Effective or Pitch Diameter = Major Diameter - .640327 x P
h = Angular Depth = 0.960491 x P
h/6 = Shortening = 0.160083 x P
P = Pitch = 1/Number of threads per inch (tpi)
r = Radius at the Crest & Root = 0.137329 x P
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BRITISH THREAD -- MINIATURE SERIES -- BA

47 deg

British Association BS 93
(note: only sizes No. 0-16 are covered by BS 93)
British Association Standard Thread.
Used mainly for instruments and clocks.
Replaced by the metric ISO thread and the ISO fine thread.

MARYLAND METRICS -- THREAD DATA CHART:
British Thread (British Association) -- Miniature Series
Nominal
Size
BA
Thread
Form
Type
Major
Diameter
mm
Pitch
mm
p
Threads
per Inch
tpi
Pitch
Diameter
mm
Minor
Diameter
Male Thd.
Thread
Height
H1
Tap Drill
Diameter
d=D d2=D2 d3 mm
No. 25 BA 0.25 0.07 363 0.205 0.18
No. 24 BA 0.29 0.08 317 0.239 0.21
No. 23 BA 0.33 0.09 282 0.272 0.24
No. 22 BA 0.37 0.10 254 0.307 0.27
No. 21 BA 0.42 0.11 230.91 0.350 0.31
No. 20 BA 0.48 0.13 211.67 0.403 0.36
No. 19 BA 0.54 0.14 181.43 0.450 0.40
No. 18 BA 0.62 0.15 169.33 0.524 0.47
No. 17 BA 0.70 0.17 149.41 0.591 0.53
No. 16 BA 0.79 0.19 133.68 0.668 0.56 0.115 0.60
No. 15 BA 0.90 0.21 120.95 0.766 0.65 0.125 0.70
No. 14 BA 1 0.23 110.4 0.853 0.72 0.14 0.75
No. 13 BA 1.2 0.25 101.6 1.040 0.9 0.15 0.95
No. 12 BA 1.3 0.28 90.71 1.121 0.96 0.17 1.00
No. 11 BA 1.5 0.32 81.93 1.301 1.13 0.185 1.20
No. 10 BA 1.7 0.35 72.57 1.476 1.28 0.21 1.35
No. 9 BA 1.9 0.39 65.12 1.650 1.43 0.235 1.50
No. 8 BA 2.2 0.43 59.07 1.925 1.68 0.26 1.80
No. 7 BA 2.5 0.48 52.92 2.193 1.92 0.29 2.00
No. 6 BA 2.8 0.53 47.92 2.461 2.16 0.32 2.30
No. 5 BA 3.2 0.59 43.05 2.822 2.49 0.355 2.60
No. 4 BA 3.6 0.66 38.48 3.177 2.81 0.395 2.95
No. 3 BA 4.1 0.73 34.79 3.633 3.22 0.44 3.40
No. 2 BA 4.7 0.81 31.35 4.181 3.73 0.485 3.90
No. 1 BA 5.3 0.90 28.22 4.724 4.22 0.54 4.40
No. 0 BA 6 1 25.4 5.360 4.8 0.6 5.00

BA thread notes:
C = Core diameter = Major Diameter - 1.2000 x P (2d)
d = Actual Depth = 0.60000 x P
Effective or Pitch Diameter = Major Diameter - 0.6000 x P (d)
h = Triangular height = 1.1363365 x P
Nuts and Bolts across flats is nominally 1.75 x Major Diameter
P = Pitch = 1/Number of threads per inch (tpi)
r = Radius at the Crest & Root = 0.1808346 x P
t = Shortening = 0.2681688 x P
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