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3/4-16 UNF bolt size
1-1/8 in wrench
across-flats spanner / socket size for 3/4-16
3/4-16 UNF bolt — heavy axles and spindles.
Full specification
| System | Imperial UNF |
| Nominal diameter | 3/4 in (19.05 mm) |
| Thread pitch | 16 TPI (fine) |
| Wrench / spanner (across flats) | 1-1/8 in |
| Tap drill | 11/16 in |
| Clearance hole | 49/64 in |
| Common grade / class | Grade 5 |
| Typical torque | 390 Nm (288 ft·lb) |
| Closest other-system size | ~3/4-10 coarse |
🔧 Torque unit converter
Pre-filled with the typical torque for 3/4-16 (Grade 5, dry). Edit any field to convert.
⚠️ Torque values here are general references for Grade 5 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 3/4-16
3/4-16 fine thread is found on heavy axle nuts and spindles.
Spindle nuts of this size often have a specific staged torque — follow the manual.
Frequently asked questions
- What size wrench or spanner fits 3/4-16?
- 3/4-16 UNF bolt uses a 1-1/8 in wrench or spanner, measured across the flats of the hex head.
- What is the torque for 3/4-16?
- A typical tightening torque for 3/4-16 UNF bolt in Grade 5 on dry threads is about 390 Nm (288 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does 3/4-16 use?
- 3/4-16 UNF bolt has a thread pitch of 16 TPI (fine) and uses a 11/16 in tap drill, with a 49/64 in clearance hole.