Machine Screw Square Nuts

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160 Products

Low-Strength Steel Square Nuts

Large flat sides make these nuts easy to grip with a wrench and keep them from rotating in channels and square holes. About half the strength of medium-strength steel square nuts, use them in light duty fastening applications, such as securing access panels.

Zinc-Plated Steel—Zinc-plated steel square nuts resist corrosion in wet environments.

Black-Zinc-Plated Steel—Black-zinc-plated steel square nuts resist corrosion in wet environments and have a black finish that blends in with dark surfaces.

Hot-Dipped Galvanized Steel—Hot-dipped galvanized steel square nuts have a thick coating for better corrosion resistance than zinc-plated steel nuts. They must be used with other hot-dipped galvanized fasteners.

Steel—Steel square nuts are best for dry environments, since moisture will cause them to rust.

	Thread Size	Wd.	Ht.	Specs. Met	Pkg. Qty.		Pkg.
Zinc-Plated Steel



		2-56	3/16"	1/16"	—	100	000000000	00000


		4-40	1/4"	3/32"	—	100	000000000	0000
		5-40	5/16"	7/64"	—	100	000000000	0000
		6-32	5/16"	7/64"	—	100	000000000	0000
		8-32	11/32"	1/8"	—	100	000000000	0000
		10-24	3/8"	1/8"	—	100	000000000	0000
		10-32	3/8"	1/8"	—	100	000000000	0000
		1/4"-20	7/16"	3/16"	—	100	000000000	0000
		1/4"-28	7/16"	3/16"	—	100	000000000	00000
		5/16"-18	9/16"	7/32"	—	100	000000000	00000
		3/8"-16	5/8"	1/4"	—	50	000000000	00000


		1/2"-13	13/16"	7/16"	—	25	000000000	0000
		5/8"-11	1"	35/64"	—	25	000000000	00000
		3/4"-10	1 1/8"	21/32"	—	10	000000000	0000
		1"-8	1 1/2"	7/8"	—	5	000000000	00000


		Black-Zinc-Plated Steel



				1/4"-20	7/16"	3/16"	—	100	000000000	00000


				5/16"-18	9/16"	7/32"	—	50	000000000	00000
				3/8"-16	5/8"	1/4"	—	50	000000000	00000


				Hot-Dipped Galvanized Steel



						5/16"-18	9/16"	17/64"	—	100	000000000	00000


						3/8"-16	5/8"	21/64"	—	100	000000000	00000
						1/2"-13	13/16"	7/16"	—	50	000000000	00000
						5/8"-11	1"	35/64"	—	25	000000000	00000
						3/4"-10	1 1/8"	21/32"	—	10	000000000	0000
						7/8"-9	1 5/16"	49/64"	—	5	000000000	0000
						1"-8	1 1/2"	7/8"	—	5	000000000	00000


						Steel



								6-32	5/16"	7/64"	—	100	000000000	0000


								8-32	11/32"	1/8"	—	100	000000000	0000
								10-24	3/8"	1/8"	—	100	000000000	0000
								10-32	3/8"	1/8"	—	100	000000000	0000
								1/4"-20	7/16"	3/16"	—	100	000000000	00000
								1/4"-20	7/16"	7/32"	—	100	000000000	0000
								5/16"-18	9/16"	7/32"	—	100	000000000	00000
								5/16"-18	9/16"	17/64"	—	100	000000000	00000
3/8"-16								5/8"	1/4"	—	100	000000000	00000
3/8"-16	5/8"							21/64"	—	100	000000000	00000
7/16"-14	3/4"							3/8"	—	25	000000000	00000


1/2"-13	13/16"							7/16"	—	50	000000000	00000
5/8"-11	1"							35/64"	—	25	000000000	00000
3/4"-10	1 1/8"							21/32"	—	10	000000000	00000
7/8"-9	1 5/16"							49/64"	—	5	000000000	00000
1"-8	1 1/2"							7/8"	—	5	000000000	00000
1 1/8"-7	1 11/16"							1"	—	1	000000000	0000
1 1/4"-7	1 7/8"							1 3/32"	—	1	000000000	0000
1 1/2"-6	2 1/4"							1 5/16"	—	1	000000000	0000


Steel—ISO Class 5



								M4 × 0.7 mm	7 mm	3 mm	DIN 557	50	000000000	0000


								M5 × 0.8 mm	8 mm	4 mm	DIN 557	50	000000000	00000
								M6 × 1 mm	10 mm	5 mm	DIN 557	25	000000000	0000
								M8 × 1.25 mm	13 mm	6.5 mm	DIN 557	25	000000000	0000
								M10 × 1.5 mm	17 mm	8 mm	DIN 557	10	000000000	0000
		M12 × 1.75 mm						19 mm	10 mm	DIN 557	5	000000000	0000


		Zinc-Plated Steel—ISO Class 5



								M4 × 0.7 mm	7 mm	3.2 mm	DIN 557	100	000000000	00000


								M5 × 0.8 mm	8 mm	4 mm	DIN 557	100	000000000	00000
								M6 × 1 mm	10 mm	5 mm	DIN 557	100	000000000	00000
				M8 × 1.25 mm				13 mm	6.5 mm	DIN 557	25	000000000	0000
				M10 × 1.5 mm	17 mm			8 mm	DIN 557	25	000000000	00000
				M12 × 1.75 mm	19 mm			10 mm	DIN 557	10	000000000	0000
				M16 × 2 mm	24 mm			13 mm	DIN 557	5	000000000	00000
				M20 × 2.5 mm	30 mm			16 mm	DIN 557	5	000000000	00000


				Black-Zinc-Plated Steel—ISO Class 5



								M4 × 0.7 mm	7 mm	3 mm	DIN 557	25	000000000	0000


								M5 × 0.8 mm	8 mm	4 mm	DIN 557	25	000000000	0000
								M6 × 1 mm	10 mm	5 mm	DIN 557	25	000000000	0000
						M8 × 1.25 mm		13 mm	6.5 mm	DIN 557	10	000000000	0000
						M10 × 1.5 mm	17 mm	8 mm	DIN 557	10	000000000	00000
						M16 × 2 mm	24 mm	13 mm	DIN 557	1	000000000	0000

18-8 Stainless Steel Square Nuts

These square nuts have good chemical resistance and may be mildly magnetic. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	2-56	3/16"	1/16"	—	100	000000000	000000


	4-40	1/4"	3/32"	—	100	000000000	00000
	6-32	5/16"	7/64"	—	100	000000000	00000
	8-32	11/32"	1/8"	—	100	000000000	00000
	10-24	3/8"	1/8"	—	100	000000000	00000
	10-32	3/8"	1/8"	—	100	000000000	00000
	1/4"-20	7/16"	3/16"	—	50	000000000	00000
	1/4"-28	7/16"	3/16"	—	25	000000000	0000
	5/16"-18	9/16"	7/32"	—	25	000000000	0000
	5/16"-24	9/16"	7/32"	—	10	000000000	0000
	3/8"-16	5/8"	1/4"	—	25	000000000	00000


	3/8"-24	5/8"	1/4"	—	10	000000000	0000
	7/16"-14	3/4"	3/8"	—	5	000000000	0000
	7/16"-20	3/4"	3/8"	—	5	000000000	00000
	1/2"-13	13/16"	7/16"	—	5	000000000	0000
	5/8"-11	1"	35/64"	—	1	000000000	0000
	3/4"-10	1 1/8"	21/32"	—	1	000000000	0000
	1"-8	1 1/2"	7/8"	—	1	000000000	00000
	M5 × 0.8 mm	8 mm	4 mm	DIN 557	50	000000000	0000
	M6 × 1 mm	10 mm	5 mm	DIN 557	50	000000000	00000
	M8 × 1.25 mm	13 mm	6.5 mm	DIN 557	25	000000000	00000


	M10 × 1.5 mm	17 mm	8 mm	DIN 557	10	000000000	0000
	M12 × 1.75 mm	19 mm	10 mm	DIN 557	5	000000000	00000
	M16 × 2 mm	24 mm	13 mm	DIN 557	1	000000000	00000

18-8 Stainless Steel Thin-Profile Square Nuts

Two-thirds the height of typical square nuts and made of 18-8 stainless steel, these metric nuts are designed for use in low-clearance applications in humid, damp, and washdown environments. They’re often called square jam nuts because they can be jammed together to hold each other in place. They’re easily gripped with a wrench due to their flat, broad sides, which also prevent them from rotating in channels and square holes. Compared to hex nuts, a greater area is in contact with the fastened surface. And compared to steel nuts, they’re slightly less strong.

Black-Oxide 18-8 Stainless Steel—Black-oxide 18-8 stainless steel nuts have a dark surface color.

DIN 562—These nuts meet DIN 562, an international standard that signifies their material and dimensions are compatible with other products and tools.

	Wd., mm	Ht., mm	Specs. Met	Pkg. Qty.		Pkg.
18-8 Stainless Steel



	M2 × 0.4 mm	4	1.2	DIN 562	25	000000000	000000


	M2.5 × 0.45 mm	5	1.6	DIN 562	25	000000000	00000
	M3 × 0.5 mm	5.5	1.8	DIN 562	50	000000000	0000
	M4 × 0.7 mm	7	2.2	DIN 562	50	000000000	00000
	M5 × 0.8 mm	8	2.7	DIN 562	50	000000000	0000
	M6 × 1 mm	10	3.2	DIN 562	50	000000000	00000
	M8 × 1.25 mm	13	4	DIN 562	25	000000000	00000
	M10 × 1.5 mm	17	5	DIN 562	10	000000000	0000


	Black-Oxide 18-8 Stainless Steel



			M3 × 0.5 mm	5.5	1.8	DIN 562	10	000000000	00000


			M4 × 0.7 mm	7	2.2	DIN 562	10	000000000	00000

Highly-Corrosion-Resistant 316 Stainless Steel Square Nuts

These square nuts have excellent resistance to chemicals and salt water. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Pkg. Qty.		Pkg.
316 Stainless Steel



	4-40	1/4"	3/32"	100	000000000	000000


	6-32	5/16"	7/64"	100	000000000	00000
	8-32	11/32"	1/8"	50	000000000	00000
	10-24	3/8"	1/8"	50	000000000	00000
	10-32	3/8"	1/8"	50	000000000	00000
	1/4"-20	7/16"	3/16"	25	000000000	00000
	1/4"-28	7/16"	3/16"	25	000000000	0000
	5/16"-18	9/16"	7/32"	10	000000000	0000
	3/8"-16	5/8"	1/4"	10	000000000	00000
	1/2"-13	13/16"	7/16"	1	000000000	0000
	5/8"-11	1"	35/64"	1	000000000	0000


	3/4"-10	1 1/8"	21/32"	1	000000000	00000

Medium-Strength Steel Thin-Profile Square Nuts

Made of ISO Class 04 steel and about two-thirds the height of standard steel square nuts, these nuts are suitable for most low-clearance fastening applications. Also known as square jam nuts, they’re commonly jammed together to hold each other in place. Their flat, broad sides make them easy to grip with a wrench and keep them from rotating in channels and square holes. Compared to hex nuts, a greater area is in contact with the fastened surface.

Black-Oxide Steel—Black-oxide steel square nuts have a dark surface color and are mildly corrosion resistant in dry environments.

Zinc-Plated Steel—Zinc-plated steel square nuts resist corrosion in wet environments.

DIN 562—These nuts meet DIN 562, an international standard that signifies their material and dimensions are compatible with other products and tools.

	Wd., mm	Ht., mm	Specs. Met	Pkg. Qty.		Pkg.
Black-Oxide Steel—ISO Class 04



	M3 × 0.5 mm	5.5	1.8	DIN 562	10	000000000	00000


	M4 × 0.7 mm	7	2.2	DIN 562	10	000000000	0000


	Zinc-Plated Steel—ISO Class 04



			M3 × 0.5 mm	5.5	1.8	DIN 562	100	000000000	0000


			M4 × 0.7 mm	7	2.2	DIN 562	100	000000000	0000
			M5 × 0.8 mm	8	2.7	DIN 562	100	000000000	00000
			M6 × 1 mm	10	3.2	DIN 562	100	000000000	00000
			M8 × 1.25 mm	13	4	DIN 562	50	000000000	00000
			M10 × 1.5 mm	17	5	DIN 562	25	000000000	00000

Brass Square Nuts

These square nuts are corrosion resistant in wet environments, electrically conductive, and nonmagnetic. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Brass



	4-40	1/4"	3/32"	100	000000000	00000


	6-32	5/16"	7/64"	100	000000000	00000
	8-32	11/32"	1/8"	50	000000000	0000
	10-24	3/8"	1/8"	50	000000000	00000
	10-32	3/8"	1/8"	50	000000000	00000
	1/4"-20	7/16"	3/16"	25	000000000	00000
	5/16"-18	9/16"	7/32"	10	000000000	0000
	3/8"-16	5/8"	1/4"	10	000000000	00000
	1/2"-13	13/16"	7/16"	5	000000000	00000

Medium-Strength Steel Square Nuts

Large flat sides make these nuts easy to grip with a wrench and keep them from rotating in channels and square holes. Made from SAE Grade 5 steel, they're suitable for fastening most machinery and equipment.

Steel—Steel square nuts are best for dry environments, since moisture will cause them to rust.

Zinc-Plated Steel—Zinc-plated steel square nuts resist corrosion in wet environments.

	Wd.	Ht.	Pkg. Qty.		Pkg.
Steel—SAE Grade 5



	1/4"-20	7/16"	7/32"	100	000000000	00000


	5/16"-18	9/16"	17/64"	50	000000000	0000
	3/8"-16	5/8"	21/64"	25	000000000	0000
	7/16"-14	3/4"	3/8"	10	000000000	0000
	1/2"-13	13/16"	7/16"	10	000000000	0000
	5/8"-11	1"	35/64"	5	000000000	0000
	3/4"-10	1 1/8"	21/32"	5	000000000	0000
	7/8"-9	1 5/16"	49/64"	1	000000000	0000
	1"-8	1 1/2"	7/8"	1	000000000	0000
	1 1/4"-7	1 7/8"	1 3/32"	1	000000000	0000


	Zinc-Plated Steel—SAE Grade 5



			1/4"-20	7/16"	7/32"	100	000000000	0000


			5/16"-18	9/16"	17/64"	100	000000000	00000
			3/8"-16	5/8"	21/64"	50	000000000	00000
			7/16"-14	3/4"	3/8"	25	000000000	00000
			1/2"-13	13/16"	7/16"	25	000000000	00000
			5/8"-11	1"	35/64"	10	000000000	0000
			3/4"-10	1 1/8"	21/32"	10	000000000	00000
			7/8"-9	1 5/16"	49/64"	5	000000000	00000
			1"-8	1 1/2"	7/8"	1	000000000	0000
			1 1/8"-7	1 11/16"	1"	1	000000000	0000
			1 1/4"-7	1 7/8"	1 3/32"	1	000000000	0000


			1 1/2"-6	2 1/4"	1 5/16"	1	000000000	00000

Fiberglass Square Nuts

These fiberglass square nuts are chemical resistant, nonconductive, and lightweight. Large flat sides make them easy to grip with a wrench and keep them from rotating in channels and square holes.

	Wd.	Ht.	Max. Temp.	Color	Pkg. Qty.		Pkg.
Fiberglass



	3/8"-16	3/4"	17/32"	Not Rated	Gray	1	000000000	00000


	1/2"-13	7/8"	41/64"	Not Rated	Gray	1	000000000	0000
	5/8"-11	1 1/8"	51/64"	Not Rated	Gray	1	000000000	0000
	3/4"-10	1 1/4"	57/64"	Not Rated	Gray	1	000000000	0000
	1"-8	1 11/16"	1 9/64"	Not Rated	Gray	1	000000000	00000

Ultra-High-Temperature Carbon Fiber Square Nuts

Unlike metal nuts, these carbon fiber square nuts won’t warp at extreme temperatures, making them ideal for heat treating and furnace fixtures. They are lightweight with an excellent strength-to-weight ratio and can be used for storage racks and shelving. Large flat sides make these nuts easy to grip with a wrench and keep them from rotating in channels and square holes. Not for use in oxidizing environments.

	Wd.	Ht.	Tensile Strength, psi	Max. Temp., ° F		Each
Carbon Fiber



	1/4"-20	1/2"	1/4"	17,000	3,990	000000000	00000


	5/16"-18	5/8"	1/4"	17,000	3,990	000000000	0000
	3/8"-16	3/4"	13/32"	17,000	3,990	000000000	00000
	1/2"-13	1"	1/2"	17,000	3,990	000000000	00000
	M6 × 1 mm	1/2"	1/4"	17,000	3,990	000000000	0000
	M8 × 1.25 mm	1/2"	1/4"	17,000	3,990	000000000	00000