Everbilt 3/8 in.-16 Zinc-Plated Carriage Bolts Review (2026)
By Nate Sawyer, Editor · Updated July 2026
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4.5$13~$8–$16 per 25-pack by length (1 in.–6 in.); nuts/washers sold separatelyCheck Price on Amazon →
- Wood joints
- Through bolting
- Playsets decks
Everbilt's 3/8 in-16 zinc carriage bolts are the clean, self-locking way to through-bolt two pieces of wood: the square shoulder sinks in so you tighten the nut with one wrench, and the domed head is tamper-resistant. But it needs a through-hole plus a separate nut and washer, only grips in wood, and the zinc finish rusts outdoors.
Pros
- Square shoulder under the head sinks into wood and self-locks, so you tighten the nut with one wrench — no second tool to hold the head
- Smooth domed head is tamper-resistant and won't snag — ideal for benches, playsets, fences and gates
- Full-length machine thread gives a strong, removable clamped joint through two pieces of wood
Cons
- Needs a through-hole plus a nut and washer (bought separately) — more parts than a lag screw
- Only grips in wood; the square shoulder spins in metal or oversized holes
- Zinc finish will rust outdoors — choose galvanized or stainless for exterior playsets and docks
Specifications
| Type | Carriage bolt (round head, square shoulder) |
|---|---|
| Sizes | 3/8 in.-16 thread; 1 in. to 6 in. long |
| Head | Domed round head, no drive (nut-tightened) |
| Material | Zinc-plated steel |
| Best for | Through-bolting wood joints |
Frequently Asked Questions
- What do you need besides the carriage bolt itself?
- A through-hole, plus a nut and washer bought separately. That is more parts than a lag screw, and forgetting the washer is the usual reason a domed head sinks unevenly into softwood.
- Why does a carriage bolt only need one wrench?
- The square shoulder under the head sinks into the wood and locks the bolt from turning, so you tighten the nut without holding the head. That only works in wood — in metal or an oversized hole the shoulder spins.
- Are zinc carriage bolts OK for a playset or dock?
- No. Zinc plating will rust outdoors; exterior playsets, fences and docks need hot-dip galvanized or stainless. The smooth domed head is tamper-resistant and snag-free, which is exactly why people want them there — just in the right material.