Machine screws are fully threaded fasteners built for precision and reliability. Whether you're repairing an appliance, assembling electronics or securing metal components, the right machine screw makes all the difference. Browse the full selection of screws and anchors at Ace Hardware to find what your project calls for.
What Are Machine Screws?
Machine screws are uniform, fully threaded fasteners designed to fasten metal to metal, either with a nut or into a pre-tapped hole. Unlike wood screws or deck screws, machine screws have consistent threading along the entire shank, making them ideal for precise, repeatable fastening in mechanical and electrical assemblies.
Machine Screw Sizes
Choosing the right machine screw size helps ensure a secure, reliable fit. Machine screws are available in both imperial and metric sizing standards.
Imperial Machine Screw Sizes
Imperial machine screws are measured by a number designation, typically ranging from #2 through #12, followed by fractional inch sizes. Common sizing examples include:
- #6: approximately 0.138 inches in diameter, ideal for light-duty electrical and hardware applications.
- #8: approximately 0.164 inches, a versatile general-purpose size.
- #10: approximately 0.190 inches, commonly used in appliances and machinery.
Metric Machine Screws Sizes
Metric machine screws use an "M" prefix to indicate the nominal outer diameter in millimeters. Popular metric sizes include:
- M4 screw: 4 mm diameter with a 0.7 mm thread pitch, a popular size for cabinetry, furniture assembly and light mechanical fastening.
- M5 screw: 5 mm diameter with a 0.8 mm thread pitch, commonly used in electronics and light mechanical assemblies.
- M6 screw: 6 mm diameter with a 1.0 mm thread pitch, a widely used size for furniture, cabinetry and light automotive work.
Types of Machine Screws
Machine screws come in several head styles to match different applications and installation needs.
- Pan head: Features a rounded top with a flat bearing surface, a reliable general-purpose option for sheet metal, electronics and mechanical assemblies
- Hex head: Driven by a wrench or socket and well suited for high-torque applications, with a six-sided head that provides a secure grip for heavy-duty mechanical and structural fastening
- Flat/countersunk head: Sits flush with the surface for a clean, finished look
- Round head: Domed profile, often used in decorative or visible assemblies
- Truss head: Wide, low-profile head that distributes load across a broader surface area
Machine Screw Materials and Finishes
Selecting the right material ensures your fasteners hold up to the demands of the job.
Stainless Steel Machine Screws
Stainless steel machine screws offer superior corrosion resistance, making them the right choice for outdoor, marine or moisture-prone environments where long-term durability matters.
Zinc Plated Machine Screws
Zinc plated machine screws provide reliable corrosion protection for indoor applications. They are a smart savings option when you need quality performance without the premium of stainless steel.
Shop Machine Screws Near You at Ace Hardware
Whether you prefer to shop from home or stop in on the way to your project, Ace makes it easy. Shop our full selection of machine screws near you at your local Ace, or shop online for fast shipping and free in-store pickup.
Explore our full hardware department for even more essentials. When your project calls for other fastener types, our helpful staff can point you toward drywall screws, construction screws, lag screws or anchors.
