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Fine Thread Sizes

 

National Fine Thread Sizes (UNF/UNRF)

Measured in Inches
Nominal Size
Major Diameter
Threads/inch
Basic Pitch Diameter
Minor Diameter
Lead Angle
at Basic Pitch Diameter
Height of Fundamental Triangle
Tensile Stress Area
 
 
 
 
 
(Degrees)
(Min)
 
(square inches)
#0
 0.060 80 0.052 0.047 4 23
0.01083
 0.002
#1
 0.073 72 0.064 0.058 3 57
0.01203
 0.003
#2
 0.086 64 0.076 0.069 3 45
0.01353
 0.004
#3
 0.099 56 0.087 0.080 3 43
0.01547
 0.005
#4
 0.112 48 0.099 0.089 3 51
0.01804
 0.007
#5
 0.125 44 0.110 0.100 3 45
0.01968
 0.008
#6
 0.138 40 0.122 0.111 3 44
0.02165
 0.010
#8
 0.164 36 0.146 0.134 3 28
0.02406
 0.015
#10
 0.190 32 0.170 0.156 3 21
0.02706
 0.020
#12
 0.216 28 0.193 0.177 3 22
0.03093
 0.026
1/4
 0.250 28 0.227 0.211 2 52
0.03093
 0.036
5/16
 0.313 24 0.285 0.267 2 40
0.03608
 0.058
3/8
 0.375 24 0.348 0.330 2 11
0.03608
 0.088
7/16
 0.438 20 0.405 0.383 2 15
0.04330
 0.119
1/2
 0.500 20 0.468 0.446 1 57
0.04330
 0.160
9/16
 0.563 18 0.526 0.502 1 55
0.04811
 0.203
5/8
 0.625 18 0.589 0.565 1 43
0.04811
 0.256
3/4
 0.750 16 0.709 0.682 1 36
0.05413
 0.373
7/8
 0.875 14 0.829 0.798 1 34
0.06186
 0.509
1
 1.000 14 0.946 0.903 1 36
0.07217
 0.663
1 1/8
 1.125 12 1.071 1.035 1 25
0.07217
 0.856
1 1/4
 1.250 12 1.196 1.160 1 16
0.07217
 1.073
1 3/8
 1.375 12 1.321 1.285 1 9
0.07217
 1.315
1 1/2
 1.500 12 1.446 1.410 1 3
0.07217
 1.581
Standards set by American Society of Mechanical Engineers