Metric Screw Gauges | McMaster-Carr

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22 Products

Screw Size Identifiers

Metric

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

	For Thread Size	For Screw Size	For Drill Bit Size	Wd.	Ht.	Thk.		Each
Metric







	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"	98728A116	000000


	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"	98728A114	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.	Thk.	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"-14, 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	3"	39"	1/2"	3	5/16"	No	20375A27	000000

Screw, Bolt, and Nut Size Identifiers


Inch/Metric	Metric

Use on external and internal fastener threads.

	For Screw Size	For Thread Pitch, mm	For Nut Size	Wd.	Ht.	Thk.		Each
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"	98845A670	00000


	Metric







					Plastic

					Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	M6, M7, M8, M10, M12, M14, M16	1, 1.25, 1.5, 1.75, 2	M10, M11, M13, M17, M19, M22, M24	5 1/4"	3 3/16"	1/64"	98845A660	0000

Thread-It Screw, Bolt, and Nut Size Identifiers

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

	For Thread Size		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"-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	20375A21	000000


	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	20375A17	00000

Threads per Inch and Thread Pitch Identifiers

Determine threads per inch and thread pitch on nuts, bolts, and other fasteners. Identifiers in a variety of sizes are riveted together in a fan design—pull one out and hold it against your threads to see if it fits. Once you’ve found a match, fold identifiers in to store them in your pocket or tool bag.

							Folded
	For Use With	For Thread Type	For Thread Location	For Threads per Inch	For Thread Pitch, mm	No. of Identifiers	Lg.	Wd.	Mfr.	Mfr. Model No.		Each
Inch/Metric







				Steel

				Screws, Bolts, Threaded Rods, Nuts	BSW/Metric	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	0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6	52	2 3/4"	1/2"	—	—	2071A111	000000


				Screws, Bolts, Threaded Rods, Nuts	BSW/Metric	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	0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7	50	2 3/4"	1/2"	—	—	2071A112	00000
				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, 0.5, 0.7, 0.75, 0.8, 0.9, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7	51	2 3/4"	1/2"	—	—	2071A68	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, 0.75, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6	28	2 3/4"	1/2"	—	—	2071A26	00000


				Metric







								Steel

								Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	—	0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.8, 1.9, 2, 2.5	28	2 1/2"	1/2"	Starrett	156M	2071A65	00000


								Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	—	0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 1, 1.1, 1.2, 1.25, 1.3, 1.4, 1.5, 1.6, 1.7, 1.75, 1.8, 1.9, 2, 2.5	28	2 3/4"	1/2"	—	—	2071A67	00000
								Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	—	0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7	22	2 3/4"	1/2"	—	—	2071A18	00000
								Screws, Bolts, Threaded Rods, Nuts	Metric	External/Internal	—	0.5, 0.75, 1, 1.1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5	27	3 1/2"	5/8"	Starrett	159M	2071A121	00000




										Stainless Steel

										Screws, Bolts, Threaded Rods, Nuts	Metric Trapezoidal	External/Internal	—	2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 16, 20	12	4 3/4"	3/4"	—	—	2071A113	00000

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	7863K1	000000

Grease Fitting Size Identifiers

Take the guesswork out of determining the thread type and size of a grease fitting. Screw the shank of a grease fitting into the labeled holes of these identifiers until you find the one that fits.

	For Thread Size	For Screw Size	For Pipe Size	Wd.	Ht.	Thk.		Each
Inch/Metric







	Aluminum

	Grease Fittings	NPT, SAE-LT, BSW, UNF, BSPT, BSF, Metric	External	3/16"-32, 1/4"-20, 1/4"-26, 1/4"-28, 5/16"-18, 5/16"-22, 5/16"-24, 3/8"-20, 3/8"-24, 1/2"-12, M6 × 0.75 mm, M6 × 1 mm, M8 × 1 mm, M8 × 1.25 mm, M10 × 1 mm, M10 × 1.5 mm	1/8", 1/4"	1/8, 1/4, 3/8	8 1/2"	3"	1/4"	6672N11	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		Container
	For Use With	For Thread Type	For Thread Location	For Threads per In.	For Thread Pitch, mm	For Acme Threads per In.	No. of Wires	Lg.	Material	Type	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, 0.6, 0.7, 0.75, 0.8, 1, 1.25, 1.5, 1.75, 2, 2.5, 3, 3.5, 4, 4.5, 5, 5.5, 6	3, 4, 5, 6, 8, 10, 12, 14, 16	48	2 3/4"	Stainless Steel	Pouch	Vinyl Plastic	2082A1	000000

Diameter Identifiers

Measure the outside diameter of small round- and hex-shaped objects such as rods, drill bits, bolts, and tubing with this pocket-size tool. This identifier has wear-resistant etched markings.

	Diameter Measuring Range					Graduation
	Inch	Metric, mm	Overall Lg.	Graduations	Color	Type	Color	With Belt Clip		Each
Inch/Metric







				Aluminum

				3/32" to 1 1/8"	4 to 26	5 1/2"	1/64", 1 mm	Blue	Etched	White	Yes	6821A1	000000

Pipe Thread and Thread Pitch Identifiers

In addition to checking NPT and BSPT pipe sizes, use the two included gauges for measuring thread pitch.

For Thread Type	For Pipe Size	For Gender	Wd.	Ht.	Thk.	Thread Size Identifier Material	Thread Pitch Identifier Material	Color		Each



Pipe	BSPT, NPT	1/8, 1/4, 3/8, 1/2, 3/4, 1, 1 1/4, 1 1/2, 2	Female, Male	9"	4 1/4"	1/4"	Plastic	Steel	Blue	5887T1	00000

Thread Gauges for Lug Nuts

Identify the most common bolt thread sizes.

Each







Aluminum

External/Internal	7/16"-20 1/2"-20 9/16"-18 M12 × 1.25 mm M12 × 1.5 mm M12 × 1.75 mm M14 × 1.25 mm M14 × 1.5 mm M14 × 2 mm M16 × 1.5 mm	4991T966	000000