Buy Carriage Bolts Apr 2026

Carriage bolts—also known as or round head square neck bolts —are specialized fasteners designed for wood-to-wood or wood-to-metal connections where a smooth, secure finish is required. They are defined by their domed, tamper-resistant heads and a square shoulder underneath that locks into the material to prevent the bolt from spinning during installation. Key Features & Benefits

: A cost-effective alternative for outdoor construction, providing a thick protective layer against the elements. Installation Tips Bolt Head Markings: What do they mean? | Fasteners 101

: The smooth, rounded head has no external drive (like a slot or hex), making it nearly impossible to grip or unscrew from the outside—ideal for security applications like locks and hinges.

: Most common for indoor furniture and dry environments. While it offers some rust protection, it may corrode over time if used in harsh outdoor settings.

: The best choice for outdoor projects, coastal areas, or damp environments. 316 stainless steel offers superior corrosion resistance compared to 304 .

: Because the head is low-profile and smooth, it reduces the risk of snagging on clothing or causing injury in high-traffic areas like decks and playground equipment. Choosing the Right Material

Selecting the correct material is critical for the longevity of your project:

: The square "neck" or shoulder just below the head bites into pre-drilled holes in wood, allowing you to tighten the nut from the opposite side using only a single wrench.