The best 1/4-20 shoulder bolt depends on the shoulder length, diameter, and quantity your assembly requires. The options below all list a 1/4-20 thread and a 5/16-inch shoulder diameter, but range from a short 1/4-inch shoulder to a longer 1-1/2-inch shoulder. Choose the S SYDIEN 1-inch set for a six-piece pack, the uxcell 5/8-inch set for a compact shoulder, or the GRAINGER APPROVED screw if a tamperproof design is the priority.
| Product | Shoulder Length | Pack Size | Best For |
|---|---|---|---|
| S SYDIEN Alloy Steel | 1 inch | 6 | General-purpose selection with listed dimensions |
| uxcell Alloy Steel | 5/8 inch | 6 | Shorter shoulder and six-piece quantity |
| S SYDIEN Alloy Steel | 3/4 inch | 6 | Intermediate shoulder length |
| uxcell Alloy Steel | 1-1/2 inches | 4 | Longer shoulder applications |
| GRAINGER APPROVED Steel | 1/4 inch | Not specified | Tamperproof fastening |
S SYDIEN 1-Inch Shoulder Bolt Set
This six-piece set has a 5/16-inch shoulder diameter, a 1-inch shoulder length, and a 1/4-20 UNC thread. The listed thread length is 0.43 inch, and the total length is 1.65 inches. Alloy steel construction and a hex socket drive are specified.
Best for: Buyers who need a 1-inch shoulder and want six bolts with stated thread and overall dimensions. It was selected as a clearly specified, mid-length option. Check that the 0.43-inch thread length suits the receiving part; it is not the same as the shoulder length.
uxcell 5/8-Inch Shoulder Bolt Set
These six alloy steel bolts have a 5/8-inch shoulder length, a 5/16-inch shoulder diameter, and a 1/4-20 UNC thread. The listing describes the material as high strength and toughness, with wear resistance and corrosion resistance. A hex socket head is intended for tightening where clearance is limited.
Best for: Assemblies that need a shorter shoulder than the 3/4- or 1-inch choices, with six pieces in the pack. Verify the required thread length and total dimensions before ordering, because those measurements are not included in the supplied features.
S SYDIEN 3/4-Inch Shoulder Bolt Set
S SYDIEN’s six-piece set has a 3/4-inch shoulder length and a 5/16-inch shoulder diameter, paired with a 1/4-20 UNC thread. The listed thread length is 0.43 inch, and the total size is 1.42 inches long. The bolts use alloy steel and a hexagon-shaped socket drive.
Best for: Buyers seeking a shoulder length between the 5/8-inch and 1-inch options. Its stated overall and thread lengths make it easier to compare against an assembly drawing. Confirm that the short listed thread length provides enough engagement for your application.
uxcell 1-1/2-Inch Shoulder Bolts
This four-piece set has a 1-1/2-inch shoulder length, 5/16-inch shoulder diameter, and 1/4-20 UNC threads. The listing identifies alloy steel and describes strength, toughness, wear resistance, and corrosion resistance. Its hex socket head supports tightening in limited-clearance locations.
Best for: Applications that call for a longer shoulder than the 1-inch option. It was selected to cover a larger shoulder-length requirement while keeping the same listed diameter and thread size. The supplied details do not state thread length or total length, so verify both before choosing it.
GRAINGER APPROVED Tamperproof Shoulder Screw
This steel shoulder screw is listed with a 1/4-20 thread, 5/16-inch shoulder diameter, and 1/4-inch shoulder length. Its distinguishing feature is the tamperproof design, which sets it apart from the hex socket choices above.
Best for: Buyers who prioritize tamper resistance and need a very short shoulder. The available product details are limited: they do not specify pack quantity, drive details, or thread length. Avoid choosing it without confirming those requirements for the intended installation.
Buying Guide: How To Choose A 1/4-20 Shoulder Bolt
What does 1/4-20 mean?
In this product list, 1/4-20 refers to the stated screw thread: a 1/4-inch nominal diameter with 20 threads per inch. The listings identify the thread as UNC. Check the mating hole or fastener specification before purchase; shoulder dimensions do not determine thread fit.
How much shoulder length do you need?
Match the shoulder length to the space or pivot surface specified in your design. The choices here span 1/4, 5/8, 3/4, 1, and 1-1/2 inches. The shoulder is the unthreaded cylindrical section, so do not confuse its length with total bolt length or threaded length.
Does pack size matter?
Pack quantity varies. The selected S SYDIEN sets list six pieces, while the longer uxcell set lists four. The GRAINGER APPROVED listing does not provide a quantity in the supplied details. Count how many fasteners the project needs and allow for any spares before selecting a pack.
Which drive style should you choose?
The S SYDIEN and uxcell options specify hex socket heads. The listings describe the socket as useful for tightening with limited clearance. The GRAINGER APPROVED item is described as tamperproof, but its supplied information does not identify the drive type. Confirm tool access and drive requirements for your installation.
Frequently Asked Questions
Are all five products 1/4-20?
Yes. Each selected product lists a 1/4-20 thread. Several identify it specifically as 1/4-20 UNC.
Do these products have the same shoulder diameter?
All five list a 5/16-inch shoulder diameter. Their shoulder lengths and other stated details differ.
Which option has the longest shoulder?
The selected uxcell set has a 1-1/2-inch shoulder, the longest among these five products.
Which option includes the most pieces?
The selected S SYDIEN sets list six bolts each, which is the largest specified pack quantity in this comparison.
Should I compare thread length before buying?
Yes. Thread length affects how much of the screw can engage the receiving part. Some listings provide this measurement and others do not, so check the product details against your required engagement.