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M18x1.5 bolt size
27 mm wrench
across-flats spanner / socket size for M18×1.5
M18x1.5 bolt — sensors, fittings and heavy joints.
Full specification
| System | Metric fine |
| Nominal diameter | 18 mm |
| Thread pitch | 1.5 mm (fine) |
| Wrench / spanner (across flats) | 27 mm |
| Tap drill | 16.5 mm |
| Clearance hole | 20 mm |
| Common grade / class | 8.8 |
| Typical torque | 320 Nm (236 ft·lb) |
| Closest other-system size | M18 coarse |
🔧 Torque unit converter
Pre-filled with the typical torque for M18×1.5 (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 M18×1.5
M18x1.5 is common for oxygen sensors and large fittings.
Anti-seize on M18x1.5 sensor threads makes future removal far easier.
Frequently asked questions
- What size wrench or spanner fits M18×1.5?
- M18x1.5 bolt uses a 27 mm wrench or spanner, measured across the flats of the hex head.
- What is the torque for M18×1.5?
- A typical tightening torque for M18x1.5 bolt in 8.8 on dry threads is about 320 Nm (236 ft·lb). Always confirm against the manufacturer spec for important joints.
- What thread pitch and tap drill does M18×1.5 use?
- M18x1.5 bolt has a thread pitch of 1.5 mm (fine) and uses a 16.5 mm tap drill, with a 20 mm clearance hole.