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3/8 inch socket cap screw size
5/16 in hex key
Allen / internal hex key size for 3/8 socket cap
3/8 inch socket cap screw — heavy tooling and fixtures.
Full specification
| System | Imperial (Alloy) |
| Nominal diameter | 3/8 in (9.53 mm) |
| Thread pitch | 16 TPI |
| Hex key (Allen) | 5/16 in |
| Tap drill | 5/16 in (7.9 mm) |
| Clearance hole | 25/64 in |
| Common grade / class | Alloy (180 ksi) |
| Typical torque | 60 Nm (44 ft·lb) |
| Closest other-system size | ~M10 |
🔧 Torque unit converter
Pre-filled with the typical torque for 3/8 socket cap (Alloy (180 ksi), dry). Edit any field to convert.
⚠️ Torque values here are general references for Alloy (180 ksi) on clean, dry threads. Lubrication, coatings, and the joint material change the figure significantly. For structural, automotive, or safety-critical work, always use the torque specified by the manufacturer or engineer.
About 3/8 socket cap
The 3/8-16 socket cap is a heavy imperial tooling fastener.
A 5/16 in hex key fits 3/8-16 socket caps.
Frequently asked questions
- What size Allen / hex key fits 3/8 socket cap?
- 3/8 inch socket cap screw uses a 5/16 in hex (Allen) key with an internal hex drive.
- What is the torque for 3/8 socket cap?
- A typical tightening torque for 3/8 inch socket cap screw in Alloy (180 ksi) on dry threads is about 60 Nm (44 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does 3/8 socket cap use?
- 3/8 inch socket cap screw has a thread pitch of 16 TPI and uses a 5/16 in (7.9 mm) tap drill, with a 25/64 in clearance hole.