UNC
= Unified National Coarse Screw Thread. This is one of three graded series: UNC (Unified National Corase); UNF (Unified National Fine); and UNEF (Unified National Extra Fine). The Nominal Major Diameter and Threads-per-inch (Pitch) are defined by ANSI/ASME B1.1 and are the choices for the customary Unified screws and
nuts.
Nominal
Major
Major
Tapping
TPI
Pitch
Diameter
Diameter
Diameter
Drill Size
mm
Inch
mm
mm
#1 - 64 UNC
0.0730
1.854
1.50
64
0.397
#2 - 56 UNC
0.0860
2.184
1.80
56
0.453
#3 - 48 UNC
0.0990
2.515
2.10
48
0.529
#4 - 40 UNC
0.1120
2.845
2.35
40
0.635
#5 - 40 UNC
0.1250
3.175
2.65
40
0.635
#6 - 32 UNC
0.1380
3.505
2.85
32
0.794
#8 - 32 UNC
0.1640
4.166
3.50
32
0.794
#10 - 24 UNC
0.1900
4.826
4.00
24
1.058
#12 - 24 UNC
0.2160
5.486
4.65
24
1.058
1/4" - 20 UNC
0.2500
6.350
5.35
20
1.270
5/16" - 18 UNC
0.3125
7.938
6.80
18
1.411
3/8" - 16 UNC
0.3750
9.525
8.25
16
1.587
7/16" - 14 UNC
0.4375
11.112
9.65
14
1.814
1/2" - 13 UNC
0.5000
12.700
11.15
13
1.954
9/16" - 12 UNC
0.5625
14.288
12.60
12
2.117
5/8" - 11 UNC
0.6250
15.875
14.05
11
2.309
3/4" - 10 UNC
0.7500
19.050
17.00
10
2.540
7/8" - 9 UNC
0.8750
22.225
20.00
9
2.822
1" - 8 UNC
1.0000
25.400
22.85
8
3.175
1-1/8" - 7 UNC
1.1250
28.575
25.65
7
3.628
1-1/4" - 7 UNC
1.2500
31.750
28.85
7
3.628
1-3/8" - 6 UNC
1.3750
43.925
31.55
6
4.233
1-1/2" - 6 UNC
1.5000
38.100
34.70
6
4.233
1-3/4" - 5 UNC
1.7500
44.450
40.40
5
5.080
2" - 4-1/2 UNC
2.0000
50.800
46.30
4.5
5.644
2-1/4" - 4-1/2 UNC
2.2500
57.150
52.65
4.5
5.644
2-1/2" - 4 UNC
2.5000
63.500
58.50
4
6.350
2-3/4" - 4 UNC
2.7500
69.850
64.75
4
6.350
3" - 4 UNC
3.0000
63.500
71.10
4
6.350
3-1/4" - 4 UNC
3.2500
82.550
77.45
4
6.350
3-1/2" - 4 UNC
3.5000
88.900
83.80
4
6.350
3-3/4" - 4 UNC
3.7500
95.250
90.15
4
6.350
4" - 4 UNC
4.0000
101.600
96.50
4
6.350
UNC Screw Thread
Disclaimer:
This data is provided for general information only. The intention
is to provide accurate information; regardless; errors may exist
in the supplied information. If accuracy is critical, base your
final decisions on the data provided in the root document: ANSI/ASME
B1.1:2003; which is a copyrighted document. To purchase a copy visit
an Authorized Reseller.
Comments:
Original Posting: 7/14/2009
Last Revision: 5/16/2016
Error corrections in, or comments about, the above data can be sent
to: office@gagecrib.com
Gage Crib Worldwide, Inc.
6701 Old 28th St SE, Suite B
Grand Rapids, MI 49546-6937
Phone: 001-616-954-6581 • Fax: 001-616-954-6583 CONTACT FORMS & INFO