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3/4-inch bolt size
1-1/8 in wrench
across-flats spanner / socket size for 3/4 in
3/4-inch bolt — major structural connections.
Full specification
| System | Imperial UNC |
| Nominal diameter | 3/4 in (19.05 mm) |
| Thread pitch | 10 TPI |
| Wrench / spanner (across flats) | 1-1/8 in |
| Tap drill | 21/32 in (16.7 mm) |
| Clearance hole | 49/64 in |
| Common grade / class | Grade 5 |
| Typical torque | 353 Nm (260 ft·lb) |
| Closest other-system size | ~M20 |
🔧 Torque unit converter
Pre-filled with the typical torque for 3/4 in (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 in
3/4-10 is a major structural bolt for steel framing and large bases.
A 1-1/8 in socket and breaker bar are needed for this size.
Frequently asked questions
- What size wrench or spanner fits 3/4 in?
- 3/4-inch 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 in?
- A typical tightening torque for 3/4-inch bolt in Grade 5 on dry threads is about 353 Nm (260 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does 3/4 in use?
- 3/4-inch bolt has a thread pitch of 10 TPI and uses a 21/32 in (16.7 mm) tap drill, with a 49/64 in clearance hole.