Bolt Size Identifiers | McMaster-Carr

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29 Products

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 Thread Pitch	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, 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
Metric
Plastic
Screws, Bolts, Threaded Rods	Metric	External	__	M2.3, M2.6, M3, M3.5, M4, M4.5, M5, M5.5, M6, M7, M8, M9, M10, M11, M12, M14, M16, M18, M20, M22, M24	0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.9 mm, 1 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2.5 mm, 3 mm	__	__	9 1/2"	4"	7/16"	0000000	00000
Steel
Screws, Bolts, Threaded Rods	Metric	External	M8 × 0.75 mm, M8 × 1 mm, M8 × 1.25 mm, M9 × 0.75 mm, M9 × 1 mm, M9 × 1.25 mm, M10 × 0.75 mm, M10 × 1 mm, M10 × 1.25 mm, M10 × 1.5 mm, M11 × 0.75 mm, M11 × 1 mm, M11 × 1.5 mm, M12 × 1 mm, M12 × 1.25 mm, M12 × 1.5 mm, M12 × 1.75 mm, M14 × 1.25 mm, M14 × 1.5 mm, M14 × 2 mm	M8, M9, M10, M11, M12, M14	__	__	__	5 1/8"	5 3/8"	1/8"	000000000	00000
Screws, Bolts, Threaded Rods, Drill Bits	Metric	External	M2 × 0.25 mm, M2 × 0.4 mm, M2.2 × 0.25 mm, M2.2 × 0.45 mm, M2.5 × 0.35 mm, M2.5 × 0.45 mm, M3 × 0.35 mm, M3 × 0.5 mm, M3.5 × 0.35 mm, M3.5 × 0.6 mm, M4 × 0.5 mm, M4 × 0.7 mm, M4.5 × 0.5 mm, M4.5 × 0.75 mm, M5 × 0.5 mm, M5 × 0.8 mm, M5.5 × 0.5 mm, M6 × 0.75 mm, M6 × 1 mm, M7 × 0.75 mm, M7 × 1 mm	M2, M2.2, M2.5, M3, M3.5, M4, M4.5, M5, M5.5, M6, M7	__	__	7/32", 52 ga, 50 ga, 48 ga, 46 ga, 45 ga, 43 ga, 39 ga, 37 ga, 32 ga, 31 ga, 30 ga, 28 ga, 25 ga, 22 ga, 21 ga, 18 ga, 16 ga, 10 ga, 8 ga, 4 ga, B, D, J	3"	5 3/8"	3/32"	000000000	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 mm, M5 × 0.8 mm, M6 × 1 mm, M7 × 1 mm, M8 × 1 mm, M8 × 1.25 mm, M10 × 1 mm, M10 × 1.25 mm, M10 × 1.5 mm, M12 × 1.25 mm, M12 × 1.5 mm, M12 × 1.75 mm, 7/16"-14	3"	39"	1/2"	3	5/16"	No	00000000	000000

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 mm, M5 × 0.8 mm, M6 × 1 mm, M7 × 1 mm, M8 × 1 mm, M8 × 1.25 mm, M10 × 1 mm, M10 × 1.25 mm, M10 × 1.5 mm, M12 × 1.25 mm, M12 × 1.5 mm, M12 × 1.75 mm	00000000	00000
Metric
Steel
Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	M3 × 0.5 mm, M4 × 0.7 mm, M5 × 0.8 mm, M6 × 1 mm, M7 × 1 mm, M8 × 1 mm, M8 × 1.25 mm, M10 × 1 mm, M10 × 1.25 mm, M10 × 1.5 mm, M12 × 1.25 mm, M12 × 1.5 mm, M12 × 1.75 mm, M14 × 1.5 mm, M14 × 2 mm, M16 × 1.5 mm, M16 × 2 mm, M20 × 1.5 mm, M20 × 2.5 mm, M24 × 2 mm, M24 × 3 mm	00000000	00000

Screw, Bolt, and Nut Size Identifiers

Inch

Inch/Metric

Metric

Use on external and internal fastener threads.

Inch
For Use With	For Thread Type	For Thread Location	For Screw Size	For Thread Pitch	For Nut Size	Wd.	Ht.	Thick.		Each
Plastic
Screws, Bolts, Threaded Rods, Nuts	__	External/Internal	No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 3/4"	__	No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8"	7 1/2"	2 3/8"	1/64"	000000000	00000
Inch/Metric
Plastic
Screws, Bolts, Threaded Rods, Nuts	__	External/Internal	No. 6, No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8", 3/4", 1", M6, M7, M8, M10, M12, M14, M16, M18, M20, M22	__	No. 8, No. 10, 1/4", 5/16", 3/8", 7/16", 1/2", 9/16", 5/8"	9"	3 3/4"	1/64"	000000000	00000
Metric
Plastic
Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	M6, M7, M8, M10, M12, M14, M16	1 mm, 1.25 mm, 1.5 mm, 1.75 mm, 2 mm	M10, M11, M13, M17, M19, M22, M24	5 1/4"	3 3/16"	1/64"	000000000	0000

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
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 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.	Manufacturer	Manufacturer Model No.		Each
Inch
Steel
Screws, Bolts, Threaded Rods	BSW	External/Internal	4, 4 1/2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 34, 36, 40, 48, 60	__	28	2 3/4"	3/4"	Mitutoyo	188-102	000000	000000
Screws, Bolts, Threaded Rods	BSW	External/Internal	4, 4 1/2, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 18, 19, 20, 22, 24, 25, 26, 28, 30, 32, 36, 40, 48, 60, 62	__	28	2 3/4"	1/2"	__	__	0000000	00000
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	00000
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
Stainless Steel
Screws, Bolts, Threaded Rods, Nuts	Acme	External/Internal	1, 1 1/3, 1 1/2, 1 3/4, 2, 2 1/2, 3, 3 1/2, 4, 5, 6, 7, 8, 9, 10, 12	__	16	4 3/4"	1"	__	__	0000000	000000
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
Metric
Steel
Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	__	0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.9 mm, 2 mm, 2.5 mm	28	2 1/2"	1/2"	Starrett	156M	0000000	00000
Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	__	0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 1 mm, 1.1 mm, 1.2 mm, 1.25 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.75 mm, 1.8 mm, 1.9 mm, 2 mm, 2.5 mm	28	2 3/4"	1/2"	__	__	0000000	00000
Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	__	0.4 mm, 0.5 mm, 0.6 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	22	2 3/4"	1/2"	__	__	0000000	00000

Acme Thread Identifiers

Identify Acme threads and use as a guide while grinding and cutting Acme threads to a 29° included angle.

Steel
For Use With	For Thread Location	For Threads per Inch	Wd.	Ht.	Thick.		Each
Screws, Bolts, Threaded Rods	External	1, 1 1/3, 1 1/2, 1 3/4, 2, 2 1/2, 3, 4, 5, 6, 7, 8, 9, 10	3 3/8"	1 5/8"	7/64"	0000000	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

All-in-One Identifiers

Find tube, pipe, fastener, wire, and drill bit sizes with one tool.

Plastic
For Use With (Number of Sizes)	Wd.	Ht.	Material		Each
Tube (9), Tube Fittings (6), Pipe (9), Pipe Fittings (6), Screws and Bolts (20), Threaded Rods, Nuts (14), Nails (11), Wire (30), Drill Bits (21)	8 11/16"	4 1/4"	Plastic	00000000	00000
Tube (11), Tube Fittings (10), Pipe (16), Pipe Fittings (10), Screws and Bolts (20), Threaded Rods, Nuts (20), Nails (16), Wire (51), Drill Bits (50)	10 1/2"	3 1/2"	Plastic	00000000	0000

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
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