Round-Top Square Nuts | McMaster-Carr

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105 Products

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

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.

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.

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

	Wd.	Ht.	Specs. Met	Pkg. Qty.		Pkg.
Hot-Dipped Galvanized Steel



	5/16"-18	9/16"	17/64"	—	100	000000000	000000


	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



			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"	—	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

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

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



	1/4"-20	7/16"	3/16"	25	000000000	000000


	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

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