UNC Thread Gauges | McMaster-Carr

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	For System of Measurement For System of Measurement

Inch

Metric

Pipe Size

Acme

	For Use With For Use With

	For Thread Type For Thread Type	Show

UNC

	For Thread Type For Thread Type	Hide

	For Thread Location For Thread Location

External

Internal

	Material Material

Steel

	Number of Identifiers Number of Identifiers

	For Threads per Inch For Threads per Inch

3
3 1/2
4
4 1/2
5
5 1/2
6
7
7 1/2
8
9
10
11
11 1/2
12
13
14
15
16
18
20
22
24
26
27
28
29
30
32
34
36
38
40
42
44
46
48
50
52
54
56
58
60
62
64
66
68
70
72
74
76
78
80
82
84

	System of Measurement System of Measurement

Inch

Metric

	Thread Size Thread Size

	For Thread Pitch For Thread Pitch

	For Screw Size For Screw Size

	Folded Length Folded Length

2 1/4"

2 3/4"

	Folded Width Folded Width

1/2"

2 1/4"

	Height Height

5 1/8"

39"

	Thickness Thickness

3/64"

5/64"

1/2"

	Width Width

3/4"

	For Diameter For Diameter

	For Drill Bit Size For Drill Bit Size

	Container Container

Folding Case

Pouch

	Mounting Hole Diameter Mounting Hole Diameter

5/16"

	Manufacturer Manufacturer

Starrett

	Manufacturer Model Number Manufacturer Model Number

C391

	Finish Finish

Satin Chrome

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13 Products

Threads per Inch and Thread Pitch Identifiers

Determine threads per inch and thread pitch on a variety of external and internal threads.

						Folded
For Use With	For Thread Type	For Thread Location	For Threads per Inch	For Thread Pitch	No. of Identifiers	Lg.	Wd.		Each
Inch
Steel
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF	External/Internal	4, 4 1/2, 5, 5 1/2, 6, 7, 8, 9, 10, 11, 11 1/2, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 27, 28, 30, 32, 34, 36, 38, 40, 42	__	30	2 3/4"	1/2"	0000000	000000
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF	External/Internal	4, 4 1/2, 5, 5 1/2, 6, 7, 8, 9, 10, 11, 11 1/2, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 27, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84	__	51	2 1/4"	2 1/4"	0000000	00000
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF	External/Internal	6, 7, 8, 9, 10, 11, 11 1/2, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 27, 28, 30, 32, 34, 36, 38, 40, 42, 48, 50, 56, 60	__	30	2 3/4"	1/2"	000000	00000
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF	External/Internal	9, 10, 11, 11 1/2, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 27, 28, 30, 32, 34, 36, 38, 40	__	22	2 3/4"	1/2"	000000	00000
Inch/Metric
Steel
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF/Metric	External/Internal	4, 4 1/2, 5, 5 1/2, 6, 7, 8, 9, 10, 11, 11 1/2, 12, 13, 14, 15, 16, 18, 20, 22, 24, 26, 28, 29, 30, 32, 34, 36, 38, 40, 42	0.4 mm, 0.5 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.9 mm, 1 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm, 6.5 mm, 7 mm	51	2 3/4"	1/2"	0000000	00000
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF/Metric	External/Internal	4, 6, 8, 10, 11, 11 1/2, 12, 13, 16, 20, 28, 32, 40, 56	0.5 mm, 0.75 mm, 1 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 6 mm	28	2 3/4"	1/2"	0000000	00000

Thread-It Screw, Bolt, and Nut Size Identifiers

Thread your fastener into holes or onto plugs for quick and accurate size identification.

Inch
For Use With	For Thread Type	For Thread Location	For Thread Size		Each
Steel
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF	External/Internal	6-32, 6-40, 8-32, 10-24, 10-32, 1/4"-20, 1/4"-28, 5/16"-18, 5/16"-24, 3/8"-16, 3/8"-24, 7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, 9/16"-12, 9/16"-18, 5/8"-11, 5/8"-18, 3/4"-10, 3/4"-16, 1"-8, 1"-12	00000000	000000
Inch/Metric
Steel
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF/Metric	External/Internal	6-32, 8-32, 10-24, 10-32, 1/4"-20, 1/4"-28, 5/16"-18, 5/16"-24, 3/8"-16, 3/8"-24, 7/16"-14, 7/16"-20, 1/2"-13, 1/2"-20, M4×0.7, M5×0.8, M6×1, M7×1, M8×1, M8×1.25, M10×1, M10×1.25, M10×1.5, M12×1.25, M12×1.5, M12×1.75	00000000	00000

Wall-Mount Thread-It Screw, Bolt, and Nut Size Identifiers

Mount to a wall for easy access, and thread your fastener into holes or onto plugs for quick and accurate size identification.

							Mounting Holes
For Use With	For Thread Type	For Thread Location	For Thread Size	Wd.	Ht.	Thick.	No. of	Hole Dia.	Fasteners Included		Each
Inch/Metric
Steel
Screws, Bolts, Threaded Rods, Nuts	UNC/UNF/Metric	External/Internal	6-32, 8-32, 10-24, 10-32, 1/4"-20, 1/4"-28, 5/16"-18, 5/16"-24, 3/8"-16, 3/8"-24, 7/16"-20, 1/2"-13, 1/2"-20, 9/16"-12, 9/16"-18, M4×0.7, M5×0.8, M6×1, M7×1, M8×1, M8×1.25, M10×1, M10×1.25, M10×1.5, M12×1.25, M12×1.5, M12×1.75, 7/16"-14	3"	39"	1/2"	3	5/16"	No	00000000	000000

Screw Size Identifiers

Inch

Find thread size, screw size, thread pitch, diameter, or drill bit size.

Inch
For Use With	For Thread Type	For Thread Location	For Thread Size	For Screw Size	For Dia.	For Drill Bit Size	Wd.	Ht.	Thick.		Each
Steel
Screws, Bolts, Threaded Rods, Pins, Rivets, Drill Bits	UNC/UNF	External	1-64, 1-72, 2-56, 2-64, 3-48, 3-56, 4-36, 4-40, 4-48, 5-40, 5-44, 6-32, 6-36, 6-40, 8-32, 8-36, 8-40, 10-24, 10-32, 12-24, 12-28, 12-32, 1/4"-20, 1/4"-28, 1/4"-32, 5/16"-18, 5/16"-24, 5/16"-32	No. 1, No. 2, 3/32", No. 3, No. 4, No. 5, 1/8", No. 6, 5/32", No. 8, 3/16", No. 10, No. 12, 7/32", 1/4", 9/32", 5/16"	0.073", 0.086", 3/32", 0.112", 1/8", 0.138", 5/32", 0.164", 3/16", 7/32", 1/4", 9/32", 5/16"	7/32", 1/4", 9/32", 5/16", 53 ga, 51 ga, 50 ga, 48 ga, 47 ga, 45 ga, 43 ga, 42 ga, 39 ga, 38 ga, 37 ga, 36 ga, 35 ga, 33 ga, 30 ga, 29 ga, 28 ga, 25 ga, 23 ga, 21 ga, 19 ga, 16 ga, 14 ga, 13 ga, 10 ga, 8 ga, 3 ga, F, I	3"	5 1/8"	5/64"	000000000	000000

Thread Identifier Sets

Set includes calipers and gauges to identify external and internal threads.

			Container
For Use With	For Thread Type	For Thread Location	Type	Material	Includes		Each
Inch, Metric, Pipe Size
Steel
Screws, Bolts, Threaded Rods, Nuts, Pipe	NPT, UNC, UNF, BSPT, BSPP, Metric	External/Internal	Folding Case	Plastic	Caliper, Instruction Book, Two Steel Angle Gauges, Two Steel Gauges	000000	000000

Threads per Inch and Center Identifiers

Identify threads per inch on external threads and find the center of your workpiece to line up thread-cutting tools. This identifier has a corrosion-resistant satin-chrome finish that reduces glare.

Inch
For Use With	For Thread Type	For Thread Location	For Threads per Inch	Lg.	Wd.	Thick.		Each
Satin-Chrome Steel
Screws, Bolts, Threaded Rods	UNC/UNF	External	14, 20, 24, 32	2 1/4"	3/4"	3/64"	0000000	000000

Threads per Inch and Thread Pitch Size Checkers

Inspect fasteners and verify threads with this checker. It includes three wires for each of the pitch diameters. Select the wire that best fits the threads; then calculate the pitch diameter with the equations provided.

							Wire
For Use With	For Thread Type	For Thread Location	For Threads per Inch	For Thread Pitch	For Acme Threads per Inch	No. of Wires	Lg.	Material	Container	Container Material		Each
Inch/Metric/Acme
Screws, Bolts, Threaded Rods, Pipe	NPT, UNC, UNF, Metric, Acme	External	3, 3 1/2, 4, 4 1/2, 5, 5 1/2, 6, 7, 7 1/2, 8, 9, 10, 11, 11 1/2, 12, 13, 14, 16, 18, 20, 24, 27, 28, 32, 36, 40, 44, 48	0.5 mm, 0.6 mm, 0.7 mm, 0.75 mm, 0.8 mm, 1 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 5.5 mm, 6 mm	3, 4, 5, 6, 8, 10, 12, 14, 16	48	2 3/4"	Stainless Steel	Pouch	Vinyl	000000	000000

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