Home › Metric Bolts › M16
M16 bolt size
24 mm wrench
across-flats spanner / socket size for M16
M16 bolt — structural steel and heavy plant.
Full specification
| System | Metric coarse |
| Nominal diameter | 16 mm |
| Thread pitch | 2.0 mm |
| Wrench / spanner (across flats) | 24 mm |
| Tap drill | 14.0 mm |
| Clearance hole | 17.5 mm |
| Common grade / class | 8.8 |
| Typical torque | 210 Nm (155 ft·lb) |
| Closest other-system size | ~5/8 inch |
🔧 Torque unit converter
Pre-filled with the typical torque for M16 (8.8, dry). Edit any field to convert.
⚠️ Torque values here are general references for 8.8 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 M16
M16 is a common structural-steel and heavy-equipment fastener.
At M16 and above, a torque wrench or calibrated tool is essential for a reliable joint.
Frequently asked questions
- What size wrench or spanner fits M16?
- M16 bolt uses a 24 mm wrench or spanner, measured across the flats of the hex head.
- What is the torque for M16?
- A typical tightening torque for M16 bolt in 8.8 on dry threads is about 210 Nm (155 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does M16 use?
- M16 bolt has a thread pitch of 2.0 mm and uses a 14.0 mm tap drill, with a 17.5 mm clearance hole.