What size wrench or spanner fits M12?

M12 bolt uses a 19 mm wrench or spanner, measured across the flats of the hex head.

What is the torque for M12?

A typical tightening torque for M12 bolt in 8.8 on dry threads is about 85 Nm (62.7 ft·lb). Always confirm against the manufacturer spec for important joints.

What thread pitch and tap drill does M12 use?

M12 bolt has a thread pitch of 1.75 mm and uses a 10.2 mm tap drill, with a 13.5 mm clearance hole.

What is M12 used for?

M12 is commonly used in heavy machinery, automotive, structural steel. It is one of the most popular sizes in its category.

What is the closest imperial size to M12?

The closest imperial size to M12 is approximately ~1/2 inch, though they are not exactly interchangeable.

Home › Metric Bolts › M12

M12 bolt size

19 mm wrench

across-flats spanner / socket size for M12

M12 bolt — Heavy machinery, automotive, structural steel.

Full specification

System	Metric coarse
Nominal diameter	12 mm
Thread pitch	1.75 mm
Wrench / spanner (across flats)	19 mm
Tap drill	10.2 mm
Clearance hole	13.5 mm
Common grade / class	8.8
Typical torque	85 Nm (62.7 ft·lb)
Closest other-system size	~1/2 inch

🔧 Torque unit converter

Newton-metres (Nm) Foot-pounds (ft·lb) Inch-pounds (in·lb)

Pre-filled with the typical torque for M12 (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 M12

Heavy machinery, automotive, structural steel.

A 10.2 mm tap drill is correct for M12 coarse thread. The standard clearance hole is 13.5 mm.

M12 is part of the ISO metric coarse thread series, defined in ISO 261. The wrench size 19 mm is measured across the flats of the hex head.

Common applications

M12 bolts are widely used in:

Heavy machinery, automotive, structural steel
General machinery and equipment assembly
Automotive components and repairs
Structural connections (when specified by engineer)
Furniture and fixture assembly

Material and grade information

The typical grade for M12 is 8.8. This indicates:

Property class 8.8: Medium carbon steel, quenched and tempered
Tensile strength: 800 MPa minimum
Yield strength: 640 MPa minimum (0.2% proof stress)
Common coatings: Zinc plated, hot-dip galvanized, or plain

Frequently asked questions

What size wrench or spanner fits M12?: M12 bolt uses a 19 mm wrench or spanner, measured across the flats of the hex head.
What is the torque for M12?: A typical tightening torque for M12 bolt in 8.8 on dry threads is about 85 Nm (62.7 ft·lb). Always confirm against the manufacturer spec for important joints.
What thread pitch and tap drill does M12 use?: M12 bolt has a thread pitch of 1.75 mm and uses a 10.2 mm tap drill, with a 13.5 mm clearance hole.
What is M12 used for?: M12 is commonly used in heavy machinery, automotive, structural steel. It is one of the most popular sizes in its category.
What is the closest imperial size to M12?: The closest imperial size to M12 is approximately ~1/2 inch, though they are not exactly interchangeable.