UNC and UNF Screw Threads

Unified Screw Threads UNC and UNF - ANSI B1.1 - Coarse series and UNF Fine series

UNC and UNF - screw threads

UNC - Unified Coarse Thread

UNC threads ANSI B1.1:

Nominal Diameter
(in)
Threads per inchMajor Diameter
(in)
Major Diameter
(mm)
Tapping Drill Size
(mm)
Pitch
(mm)
1 64 0.073 1.854 1.50 0.397
2 56 0.086 2.184 1.80 0.453
3 48 0.099 2.515 2.10 0.529
4 40 0.112 2.845 2.35 0.635
5 40 0.125 3.175 2.65 0.635
6 32 0.138 3.505 2.85 0.794
8 32 0.164 4.166 3.50 0.794
10 24 0.190 4.826 4.00 1.058
12 24 0.216 5.486 4.65 1.058
1/4" 20 0.250 6.350 5.35 1.270
5/16" 18 0.313 7.938 6.80 1.411
3/8" 16 0.375 9.525 8.25 1.587
7/16" 14 0.438 11.112 9.65 1.814
1/2" 13 0.500 12.700 11.15 1.954
9/16" 12 0.563 14.288 12.60 2.117
5/8" 11 0.625 15.875 14.05 2.309
3/4" 10 0.750 19.050 17.00 2.540
7/8" 9 0.875 22.225 20.00 2.822
1" 8 1.000 25.400 22.85 3.175
1 1/8" 7 1.125 28.575 25.65 3.628
1 1/4" 7 1.250 31.750 28.85 3.628
1 3/8" 6 1.375 43.925 31.55 4.233
1 1/2" 6 1.500 38.100 34.70 4.233
1 3/4" 5 1.750 44.450 40.40 5.080
2" 4 1/2 2.000 50.800 46.30 5.644
2 1/4" 4 1/2 2.250 57.150 52.65 5.644
2 1/2" 4 2.500 63.500 58.50 6.350
2 3/4" 4 2.750 69.850 64.75 6.350
3" 4 3.000 76.200 71.10 6.350
3 1/4" 4 3.250 82.550 77.45 6.350
3 1/2" 4 3.500 88.900 83.80 6.350
3 3/4" 4 3.750 95.250 90.15 6.350
4" 4 4.000 101.600 96.50 6.350

UNF - Unified National Fine Thread

UNF threads ANSI B1.1:

Nominal Diameter
(in)
Threads per inchMajor Diameter 
(in)
Major Diameter
(mm)
Tapping Drill Size
(mm)
Pitch
(mm)
0 80 0.060 1.524 1.25 0.317
1 72 0.073 1.854 1.55 0.353
2 64 0.068 2.184 1.90 0.397
3 56 0.099 2.515 2.15 0.453
4 48 0.112 2.845 2.40 0.529
5 44 0.125 3.175 2.70 0.577
6 40 0.138 3.505 2.95 0.635
8 36 0.164 4.166 3.50 0.705
10 32 0.190 4.826 4.10 0.794
12 28 0.216 5.486 4.70 0.907
1/4" 28 0.250 6.350 5.50 0.907
5/16" 24 0.313 7.938 6.90 1.058
3/8" 24 0.375 9.525 8.50 1.058
7/16" 20 0.438 11.112 9.90 1.270
1/2" 20 0.500 12.700 11.50 1.270
9/16" 18 0.563 14.288 12.90 1.411
5/8" 18 0.625 15.875 14.50 1.411
3/4" 16 0.750 19.050 17.50 1.587
7/8" 14 0.875 22.225 20.40 1.814
1" 12 1.000 25.400 23.25 2.117
1 1/8" 12 1.125 28.575 26.50 2.117
1 1/4" 12 1.250 31.750 29.50 2.117
1 3/8" 12 1.375 43.925 32.75 2.117
1 1/2" 12 1.500 38.100 36.00 2.117

Related Topics

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