Round-Top Square Nuts | McMaster-Carr

Filter by

System of Measurement

Thread Size

Material

Width

Height

Finish

Hot-Dipped Galvanized

Zinc Plated

Fastener Strength Grade/Class

Thread Type

Thread Pitch

Thread Spacing

Fastener Strength Rating

Low

Medium

DFARS Specialty Metals

REACH

RoHS

Compliant with Exemptions

Not Compliant

Export Control Classification Number (ECCN)

EAR99

Thread Fit

Metric Class 7H

Unified Standard Class 2B

Forward

How can we improve?

105 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.

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

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

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

Super-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

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