The best 3-inch bolt and nut set depends on the required thread diameter, material, and washer arrangement. These options range from small 1/4-inch stainless steel hardware to a heavy-diameter 7/8-inch bolt kit. The 3/8-inch set suits buyers who want a portable case, while the 5/16-inch sets offer different quantities and package configurations. Check the mating part’s hole size and thread specification before choosing; a bolt’s 3-inch length does not indicate its diameter.
| Product | Size | Best For |
|---|---|---|
| Skvltvfyt stainless set | 1/4-20 x 3 inches | Small hardware and larger quantities |
| 304 stainless kit | 3/8-16 x 3 inches | Buyers wanting an organized case |
| 5/16-inch 304 stainless kit | 5/16-18 x 3 inches | Compact, organized sets |
| Metalsuberg alloy steel kit | 7/8-9 x 3 inches | Large-diameter fastening needs |
| QXSKSLH stainless set | 5/16-18 x 3 inches | Buyers needing extra 5/16-inch sets |
Skvltvfyt 1/4-20 Stainless Steel Set
This set contains 16 fully threaded 1/4-20 bolts, each 3 inches long, plus 16 hex nuts, flat washers, and spring lock washers. The listed material is 18-8 (304) stainless steel, described as resistant to corrosion and chemicals.
Best for: Buyers who need a relatively small 1/4-inch diameter and multiple complete hardware sets. It was selected for its clearly stated thread size and included washer types.
Check before buying: The 1/4-inch diameter is smaller than the other listed options. Avoid it if the assembly calls for a larger bolt or a different thread pitch.
3/8-16 Stainless Kit With Storage Case
This 304 stainless steel kit includes five 3/8-16 x 3-inch hex bolts, five matching nuts, five flat washers, and five spring lock washers. The package also includes a transparent plastic case for keeping the hardware together.
Best for: Buyers who need a 3/8-inch bolt and prefer a small, organized kit for a toolbox or job site. Its stated size and included washers make it easy to compare with other complete sets.
Check before buying: The set contains five bolts. Choose another option if you need a larger quantity or a different diameter.
5/16-18 Stainless Kit With Case
This kit provides six 5/16-18 x 3-inch hex bolts, six matching nuts, six flat washers, and six spring lock washers. The listed material is 304 stainless steel, and the hardware is supplied in a transparent plastic case.
Best for: DIYers who need a 5/16-inch diameter and want a complete, organized set. It offers one more bolt set than the listed 3/8-inch case kit.
Check before buying: Confirm that the required thread is 18 TPI. A 5/16-inch bolt with a different pitch may not fit the intended nut or threaded hole.
Metalsuberg 7/8-Inch Alloy Steel Bolt Kit
This four-piece kit is for a substantially larger fastener: a 7/8-9 UNC bolt with a 3-inch length measured excluding the head. The bolt is partially threaded and comes with a nylon-insert hex lock nut and a large flat washer. The listing identifies the material as alloy steel and describes a colored galvanized surface treatment.
Best for: Buyers whose application specifically requires a 7/8-inch coarse-thread bolt and the included locking nut. It stands apart from the smaller stainless steel sets by diameter and hardware configuration.
Check before buying: This is not a general substitute for 1/4-, 5/16-, or 3/8-inch bolts. Verify the required dimensions and finish for the installation.
QXSKSLH 5/16-18 Stainless Steel Set
This package includes 10 5/16-18 x 3-inch bolts, 10 hex nuts, 10 flat washers, and 10 lock washers. The product listing specifies 304 stainless steel and describes the bolts as having 18 TPI.
Best for: Buyers who need more 5/16-inch hardware sets than a six-piece kit provides. It was selected as a quantity-focused alternative with a stated material and thread specification.
Check before buying: The listed package uses 5/16-18 threads. Do not assume it fits another 5/16-inch thread pitch.
Buying Guide: Choosing A 3-Inch Bolt And Nut
Which diameter and thread should I choose?
Match the bolt diameter and thread pitch to the existing nut, threaded hole, or project specification. The options here include 1/4-20, 5/16-18, 3/8-16, and 7/8-9 UNC. These sizes are not interchangeable. If replacing an existing fastener, check its markings or measure it rather than selecting by length alone.
What does 3-inch length mean?
For most hex bolts, length is measured from beneath the head to the end of the bolt. The 7/8-inch product specifically says its 3-inch length excludes the head. Check the product’s measurement description and account for the thickness of the parts and washers being joined.
Should I choose stainless steel or alloy steel?
The four smaller kits list 304 stainless steel, with product descriptions noting corrosion resistance. The 7/8-inch kit lists alloy steel and a galvanized surface treatment. Choose based on the project’s specified material and environment; do not treat the listed materials as interchangeable.
Do I need washers or a locking nut?
Several sets include flat and spring lock washers. The 7/8-inch kit instead includes a large flat washer and a nylon-insert lock nut. Check the assembly requirements to see which components are needed, and confirm that the nut matches the bolt’s diameter and thread.
Frequently Asked Questions
Does “3-inch bolt” refer to diameter?
No. In these product names, 3 inches refers to bolt length. Diameter is listed separately, such as 1/4 inch, 5/16 inch, or 3/8 inch.
Can I use a 5/16-18 nut on a 5/16-inch bolt with another pitch?
Not necessarily. The diameter may match while the thread pitch differs. Match both the nominal diameter and thread specification.
Are all five products stainless steel?
No. Four list 304 stainless steel. The 7/8-inch Metalsuberg product lists alloy steel with a colored galvanized surface treatment.
Which set includes the most bolts?
The Skvltvfyt set lists 16 bolts. The QXSKSLH set lists 10, the 5/16-inch case kit lists six, the 3/8-inch case kit lists five, and the Metalsuberg kit lists four.
Are washers included with every option?
Yes, each listing describes at least one type of washer. Most include flat washers, while several also include spring lock washers; the 7/8-inch kit includes a large flat washer and nylon lock nut.