McMaster-Carr logo
    Enter e-mail addresses in the fields below
    Message
    Cancel
    Comments
    E-mail address (if you would like a response)
    161 Products

    Low-Strength Steel Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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"__10000000000000000
    4-40
    1/4"3/32"__1000000000000000
    5-40
    5/16"7/64"__1000000000000000
    6-32
    5/16"7/64"__1000000000000000
    8-32
    11/32"1/8"__1000000000000000
    10-24
    3/8"1/8"__1000000000000000
    10-32
    3/8"1/8"__1000000000000000
    1/4"-20
    7/16"3/16"__1000000000000000
    1/4"-28
    7/16"3/16"__10000000000000000
    5/16"-18
    9/16"7/32"__10000000000000000
    3/8"-16
    5/8"1/4"__5000000000000000
    1/2"-13
    13/16"7/16"__250000000000000
    5/8"-11
    1"35/64"__2500000000000000
    3/4"-10
    1 1/8"21/32"__100000000000000
    1"-8
    1 1/2"7/8"__500000000000000
     
    Black Zinc-Plated Steel
    1/4"-20
    7/16"3/16"__10000000000000000
    5/16"-18
    9/16"7/32"__5000000000000000
    3/8"-16
    5/8"1/4"__5000000000000000
     
    Hot-Dipped Galvanized Steel
    5/16"-18
    9/16"17/64"__10000000000000000
    3/8"-16
    5/8"21/64"__10000000000000000
    1/2"-13
    13/16"7/16"__5000000000000000
    5/8"-11
    1"35/64"__2500000000000000
    3/4"-10
    1 1/8"21/32"__100000000000000
    7/8"-9
    1 5/16"49/64"__50000000000000
    1"-8
    1 1/2"7/8"__500000000000000
     
    Steel
    6-32
    5/16"7/64"__1000000000000000
    8-32
    11/32"1/8"__1000000000000000
    10-24
    3/8"1/8"__1000000000000000
    10-32
    3/8"1/8"__1000000000000000
    1/4"-20
    7/16"3/16"__10000000000000000
    1/4"-20
    7/16"7/32"__1000000000000000
    5/16"-18
    9/16"7/32"__10000000000000000
    5/16"-18
    9/16"17/64"__10000000000000000
    3/8"-16
    5/8"1/4"__10000000000000000
    3/8"-16
    5/8"21/64"__10000000000000000
    7/16"-14
    3/4"3/8"__2500000000000000
    1/2"-13
    13/16"7/16"__5000000000000000
    5/8"-11
    1"35/64"__2500000000000000
    3/4"-10
    1 1/8"21/32"__1000000000000000
    7/8"-9
    1 5/16"49/64"__500000000000000
    1"-8
    1 1/2"7/8"__500000000000000
    1 1/8"-7
    1 11/16"1"__10000000000000
    1 1/4"-7
    1 7/8"1 3/32"__10000000000000
    1 1/2"-6
    2 1/4"1 5/16"__10000000000000
     
    Steel—ISO Class 5
    M4 × 0.7 mm7 mm3 mmDIN 557500000000000000
    M5 × 0.8 mm8 mm4 mmDIN 5575000000000000000
    M6 × 1 mm10 mm5 mmDIN 557250000000000000
    M8 × 1.25 mm13 mm6.5 mmDIN 557250000000000000
    M10 × 1.5 mm17 mm8 mmDIN 557100000000000000
    M12 × 1.75 mm19 mm10 mmDIN 55750000000000000
     
    Zinc-Plated Steel—ISO Class 5
    M4 × 0.7 mm7 mm3.2 mmDIN 55710000000000000000
    M5 × 0.8 mm8 mm4 mmDIN 55710000000000000000
    M6 × 1 mm10 mm5 mmDIN 55710000000000000000
    M8 × 1.25 mm13 mm6.5 mmDIN 557250000000000000
    M10 × 1.5 mm17 mm8 mmDIN 5572500000000000000
    M12 × 1.75 mm19 mm10 mmDIN 557100000000000000
    M16 × 2 mm24 mm13 mmDIN 557500000000000000
    M20 × 2.5 mm30 mm16 mmDIN 557500000000000000
     
    Black Zinc-Plated Steel—ISO Class 5
    M4 × 0.7 mm7 mm3 mmDIN 557250000000000000
    M5 × 0.8 mm8 mm4 mmDIN 557250000000000000
    M6 × 1 mm10 mm5 mmDIN 557250000000000000
    M8 × 1.25 mm13 mm6.5 mmDIN 557100000000000000
    M10 × 1.5 mm17 mm8 mmDIN 5571000000000000000
    M16 × 2 mm24 mm13 mmDIN 55710000000000000
     

    Medium-Strength Steel Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread
    Size
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    Steel—SAE Grade 5
    1/4"-20
    7/16"7/32"10000000000000000
    5/16"-18
    9/16"17/64"500000000000000
    3/8"-16
    5/8"21/64"250000000000000
    7/16"-14
    3/4"3/8"100000000000000
    1/2"-13
    13/16"7/16"100000000000000
    5/8"-11
    1"35/64"50000000000000
    3/4"-10
    1 1/8"21/32"50000000000000
    7/8"-9
    1 5/16"49/64"10000000000000
    1"-8
    1 1/2"7/8"10000000000000
    1 1/4"-7
    1 7/8"1 3/32"10000000000000
     
    Zinc-Plated Steel—SAE Grade 5
    1/4"-20
    7/16"7/32"1000000000000000
    5/16"-18
    9/16"17/64"10000000000000000
    3/8"-16
    5/8"21/64"5000000000000000
    7/16"-14
    3/4"3/8"2500000000000000
    1/2"-13
    13/16"7/16"2500000000000000
    5/8"-11
    1"35/64"100000000000000
    3/4"-10
    1 1/8"21/32"1000000000000000
    7/8"-9
    1 5/16"49/64"500000000000000
    1"-8
    1 1/2"7/8"10000000000000
    1 1/8"-7
    1 11/16"1"10000000000000
    1 1/4"-7
    1 7/8"1 3/32"10000000000000
    1 1/2"-6
    2 1/4"1 5/16"100000000000000
     

    Medium-Strength Steel Thin-Profile Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    Black-Oxide Steel—ISO Class 04
    M3 × 0.5 mm5.51.8DIN 5621000000000000000
    M4 × 0.7 mm72.2DIN 562100000000000000
     
    Zinc-Plated Steel—ISO Class 04
    M3 × 0.5 mm5.51.8DIN 5621000000000000000
    M4 × 0.7 mm72.2DIN 5621000000000000000
    M5 × 0.8 mm82.7DIN 56210000000000000000
    M6 × 1 mm103.2DIN 56210000000000000000
    M8 × 1.25 mm134DIN 5625000000000000000
    M10 × 1.5 mm175DIN 5622500000000000000
     

    18-8 Stainless Steel Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread Size
    Wd.
    Ht.
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    2-56
    3/16"1/16"__100000000000000000
    4-40
    1/4"3/32"__10000000000000000
    6-32
    5/16"7/64"__10000000000000000
    8-32
    11/32"1/8"__10000000000000000
    10-24
    3/8"1/8"__10000000000000000
    10-32
    3/8"1/8"__10000000000000000
    1/4"-20
    7/16"3/16"__5000000000000000
    1/4"-28
    7/16"3/16"__250000000000000
    5/16"-18
    9/16"7/32"__250000000000000
    5/16"-24
    9/16"7/32"__100000000000000
    3/8"-16
    5/8"1/4"__2500000000000000
    3/8"-24
    5/8"1/4"__100000000000000
    7/16"-14
    3/4"3/8"__50000000000000
    7/16"-20
    3/4"3/8"__500000000000000
    1/2"-13
    13/16"7/16"__50000000000000
    5/8"-11
    1"35/64"__10000000000000
    3/4"-10
    1 1/8"21/32"__10000000000000
    1"-8
    1 1/2"7/8"__100000000000000
    M5 × 0.8 mm8 mm4 mmDIN 557500000000000000
    M6 × 1 mm10 mm5 mmDIN 5575000000000000000
    M8 × 1.25 mm13 mm6.5 mmDIN 5572500000000000000
    M10 × 1.5 mm17 mm8 mmDIN 557100000000000000
    M12 × 1.75 mm19 mm10 mmDIN 557500000000000000
    M16 × 2 mm24 mm13 mmDIN 55710000000000000
     

    18-8 Stainless Steel Thin-Profile Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread Size
    Wd.,
    mm
    Ht.,
    mm
    Specs.
    Met
    Pkg.
    Qty.
    Pkg.
    18-8 Stainless Steel
    M2 × 0.4 mm41.2DIN 56225000000000000000
    M2.5 × 0.45 mm51.6DIN 5622500000000000000
    M3 × 0.5 mm5.51.8DIN 562500000000000000
    M4 × 0.7 mm72.2DIN 5625000000000000000
    M5 × 0.8 mm82.7DIN 562500000000000000
    M6 × 1 mm103.2DIN 5625000000000000000
    M8 × 1.25 mm134DIN 5622500000000000000
    M10 × 1.5 mm175DIN 562100000000000000
     
    Black-Oxide 18-8 Stainless Steel
    M3 × 0.5 mm5.51.8DIN 5621000000000000000
    M4 × 0.7 mm72.2DIN 5621000000000000000
     

    Super-Corrosion-Resistant 316 Stainless Steel Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread
    Size
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    316 Stainless Steel
    4-40
    1/4"3/32"100000000000000000
    6-32
    5/16"7/64"10000000000000000
    8-32
    11/32"1/8"5000000000000000
    10-24
    3/8"1/8"5000000000000000
    10-32
    3/8"1/8"5000000000000000
    1/4"-20
    7/16"3/16"2500000000000000
    1/4"-28
    7/16"3/16"250000000000000
    5/16"-18
    9/16"7/32"100000000000000
    3/8"-16
    5/8"1/4"1000000000000000
    1/2"-13
    13/16"7/16"10000000000000
    5/8"-11
    1"35/64"10000000000000
    3/4"-10
    1 1/8"21/32"100000000000000
     

    Ultra-High-Temperature Carbon Fiber Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread Size
    Wd.
    Ht.
    Tensile Strength,
    psi
    Max. Temp.,
    ° F
    Each
    Carbon Fiber
    1/4"-20
    1/2"1/4"17,0003,63000000000000000
    5/16"-18
    5/8"1/4"17,0003,6300000000000000
    3/8"-16
    3/4"13/32"17,0003,63000000000000000
    1/2"-13
    1"1/2"17,0003,63000000000000000
    M6 × 1 mm1/2"1/4"17,0003,6300000000000000
    M8 × 1.25 mm1/2"1/4"17,0003,63000000000000000
     

    Brass Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread
    Size
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    Brass
    4-40
    1/4"3/32"100000000000000000
    6-32
    5/16"7/64"10000000000000000
    8-32
    11/32"1/8"5000000000000000
    10-24
    3/8"1/8"5000000000000000
    10-32
    3/8"1/8"5000000000000000
    1/4"-20
    7/16"3/16"2500000000000000
    5/16"-18
    9/16"7/32"1000000000000000
    3/8"-16
    5/8"1/4"1000000000000000
    1/2"-13
    13/16"7/16"500000000000000
     

    Fiberglass Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. 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.
    Thread
    Size
    Wd.
    Ht.
    Max.
    Temp.
    Color
    Pkg.
    Qty.
    Pkg.
    Fiberglass
    3/8"-16
    3/4"17/32"Not RatedGray100000000000000
    1/2"-13
    7/8"41/64"Not RatedGray10000000000000
    5/8"-11
    1 1/8"51/64"Not RatedGray10000000000000
    3/4"-10
    1 1/4"57/64"Not RatedGray10000000000000
    1"-8
    1 11/16"1 9/64"Not RatedGray10000000000000
     

    Concave Steel Square Nuts
    3D CAD models available

    Image of Product. Front orientation. Square Nuts. Concave Steel Square Nuts.
    Also known as utility-pole nuts, these square nuts have a cupped shape that ensures a flush fit against curved surfaces and corners that bite into soft materials to resist loosening. Made from hot-dipped galvanized steel, they have a thick coating to resist corrosion in wet environments. They must be used with other hot-dipped galvanized fasteners.
    Thread
    Size
    Wd.
    Ht.
    Pkg.
    Qty.
    Pkg.
    Hot-Dipped Galvanized Steel
    3/8"-16
    5/8"7/32"25000000000000000
     
    back to top