Bolts and nuts are the basic components of fasteners; however, many people confuse these components. Bolts have external male threads and are usually used with nuts which have internal female threads. When they are bolted together they pinch materials about the two ends and thus create a strong joint, preventing axial movement. The correct nut and bolt to use for a project is determined by the load, materials to be fastened and environmental conditions. This guide offered by Jade Alloys explores the differences between nuts and bolts and a rundown of the most common types and materials. When comparing common bolts and nuts for a project, make sure to start with the size and grade of the nut bolt required for the specific project.
Bolts and Nuts : What’s the Difference?
Bolts are non-tapered fasteners that pass through pre-drilled holes. They work best in heavy-duty applications because their threads offer strong holding power. Most bolts require a nut and washer to distribute the load evenly across the joint. Screws, by contrast, are usually tapered and often create their own mating thread in wood or plastic; they are ideal for lighter applications. A matched nut bolt pair spreads the load and keeps parts aligned, which is why bolts and nuts are preferred in structural joints.
A nut’s main job is to clamp down on the bolt’s threads. Because the weakest shear plane in the thread profile governs the joint’s strength, nuts and bolts should be made from the same alloy and the nut’s tensile strength should meet or exceed that of the bolt. For critical connections, industry guidelines suggest choosing nuts that exceed the bolt’s tensile strength by about 20%. When selecting hardware, review types of bolts and types of nuts to ensure compatibility; if you’re sourcing parts, many suppliers also offer nuts and bolts online for convenient ordering.
Types of Bolts
Different bolts are designed for specific jobs. Below are common bolt head styles and specialised bolts. Use these descriptions as a quick reference when selecting fasteners online or in store.
| Bolt type | Key features | Typical uses |
| Hex bolts | Six‑sided head; can be fully or partially threaded. Offers excellent grip for wrenches. | Machinery and construction projects, general metal‑to‑metal connections |
| Anchor bolts | Embed into concrete to secure structural components. | Fixing beams or frames to foundations |
| Blind bolts | Locking fasteners for applications with access on only one side. | Structural steelwork where only one side is reachable |
| Double‑end or stud bolts | Threads at both ends. | Joining flanges or pipes |
| Carriage bolts | Domed head with square neck; designed to stop the bolt from turning. | Wood‑to‑wood or wood‑to‑metal connections where a smooth head is preferred |
| U‑bolts | Shaped like the letter U, threaded on both ends. | Supporting pipes, securing rope and chain, automotive and pipework |
| Lag bolts (lag screws) | Heavy‑duty screws with a hex head; used without nuts. | Flooring, decking and connections requiring high pull‑out strength |
| Structural fasteners | Available in sizes from a few millimetres to over 20 inches; many grades. | Replacing traditional lag and carriage bolts; professional construction projects |
| Eye bolts | Loop or eye at one end; forged or bent. | Rigging, anchoring, hoisting and lifting applications |
| Penta‑head and security bolts | Five‑sided head resists tampering. | Manhole covers, ground lids and security installations |
| T‑slot bolts | T‑shaped head that slides into a recessed slot. | Automotive assembly, construction fixtures where bolts must not turn |
| Shoulder bolts | Smooth unthreaded shoulder acts as axle. | Machinery where a rotating part is supported on the shoulder |
| J‑bolts | Hook‑shaped; threads at one end. | Roofing, securing walls to concrete foundations |
| Flange bolts | Built‑in washer distributes load. | Plumbing pipes, engine and transmission connections |
When choosing bolts online, remember to match the diameter, length and head style to the application. For example, hex bolts and carriage bolts are popular for general structural work, while eye bolts are essential for lifting tasks.
For quick ordering, search by types of bolts along with grade and coating.
Types of Nuts
Most nuts are hexagonal because six sides allow for easy tightening with a wrench and only require a one‑sixth turn to move to the next flat. However, other shapes exist to serve specific purposes. Here are common hardware nuts you will encounter:
| Nut type | Description | Common applications |
| Cap (acorn) nuts | Dome‑shaped top protects bolt threads and gives a neat finish. Also called acorn or dome nuts. | Covering exposed rod ends on shafts, axles or decorative fixtures |
| Hex nuts | The standard six‑sided nut used with many bolt types. Variations include finished hex, semi‑finished hex, hex flange and slotted hex. | General fastening in automotive, machinery and construction |
| Jam nuts | Low‑profile nut roughly half the height of a standard hex nut. Often paired with a standard nut to prevent loosening. | Locking assemblies when space is limited |
| Flange nuts | Built‑in flange acts as washer to distribute load. | Automotive exhaust systems and machinery |
| Coupling (extension) nuts | Long, hollow threaded nut used to join two threaded rods. | Extending threaded rods or connecting pipes |
| Nyloc (nylon lock) nuts | Insert of nylon creates friction to resist loosening. Also known as prevailing torque or lock nuts. | White goods, electronics, vehicles and vibrating machinery |
| Square nuts | Four‑sided; more surface in contact with material. Provide high resistance to loosening. | Used with square‑headed bolts in furniture and vintage machinery |
| T‑nuts | Flange with prongs sinks into wood or plastic for flush finish. | Furniture and woodworking |
| Slotted and castle nuts | Slots or turret shape accept cotter pins for locking. | Automotive and machinery where vibration is constant |
| Keps‑K lock nuts | Integrally attached serrated washer creates tension. | Quick assembly in household appliances; avoid over‑tightening |
| Prevailing torque nuts | Distorted top threads create friction. | Applications subject to shock and vibration |
| Kwik push‑on nuts | Plastic push‑on nut for quick assembly. | Light applications where speed is more important than reuse |
| Speed nuts | Two metal pieces function as one; also known as sheet metal nuts. | Securing panels and thin sheet metal |
| Wing nuts | Wings allow hand‑tightening; no tools required. | Situations requiring frequent removal where vibration is minimal |
| Tee nuts | Pronged flange and long body sink into material. | Wood and composite materials |
When choosing nuts, remember to select the same thread pitch and diameter as your bolts. For secure joints, use washers to distribute the load and protect surfaces from damage. If you’re comparing types of nuts for a repair, check the material, thread class and any locking feature.
Nuts and Bolts Materials
The choice of material affects the strength, corrosion resistance and cost of nuts and bolts. According to engineering guides, the nut should meet or exceed the bolt’s tensile strength. Here are the common materials:
- Stainless steel – A strong, corrosion‑resistant alloy suitable for humid environments and electrical or mechanical applications.
- Alloy steel – Typically heat‑treated for high strength; used in high‑stress applications.
- Low‑carbon steel – Inexpensive and easily machined; adequate for light‑duty applications.
- Medium‑carbon steel – Offers improved strength and toughness over low‑carbon steel.
- Titanium – Extremely strong and lightweight; resists corrosion but is expensive.
- Polymers (e.g., nylon) – Lower strength than metals but excellent chemical resistance; ideal for electronics and where weight matters.
Finish Options of bolts and nuts:
Finishes and coatings protect fasteners from corrosion and provide added benefits:
- Zinc coating – Most common; low‑cost protection against rust and corrosion.
- Galvanized finish – Provides superior corrosion resistance and anti‑seize properties, though the upfront cost is higher.
- Stainless finish – Excellent for humid or harsh environments; strong and ideal for electrical or mechanical uses.
- Black or oxide coating – Adds a dark colour, improves grip and reduces light reflection.
- Chrome plating (noted in some guides) – Gives a bright appearance and additional corrosion protection.
When selecting materials and finishes, consider the environment (indoor vs outdoor), exposure to moisture or chemicals, and aesthetic requirements. For example, stainless steel bolts and nuts with a polished finish suit marine environments, while galvanized bolts are common in outdoor construction.
Making the Right Nuts and Bolts Choice
Whether you are ordering nuts and bolts online or picking fasteners at the hardware store, it is important to understand the differences between various types of bolts and types of nuts in order to make a well-informed decision.Bolts are very strong in tensile and almost always require a nut and washer to spread the load.Nuts come in different shapes such as hexagonal, dome, lock, flange, coupling, etc. depending on the different applications.Properly chosen fastener material and finish of your project will ensure reliability and safety of your project over the years.It is recommended to check thread compatibility, use bolts and nuts with the same or stronger strength and take into account the purpose of the fastener.
Jade Alloys has an extensive range of bolts and nuts including hex bolts, eye bolts, carriage bolts and various lock nuts, available in different materials and finishes.If you need help in choosing the right fasteners for your project, please contact our experts or have a look at our catalogue.You can also shop for our nuts and bolts online which are available from our stocks for prompt delivery.
