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M30 Bolt Specifications

Reviewed by MLC Editorial Team | 31 May 2026

Verified by Rachel Mayfield, Supply Chain Analyst - May 2026

Close-up image of three steel bolts standing upright against a contrasting yellow background. — Photo by Győző Mórocz on Pexels

Every dimension, torque value, and thread specification for the M30 metric bolt in one reference card. M30 Bolt Specifications M30 is one of the most common metric fastener sizes in UK engineering, used across heavy structural and high-load joints.

Property	Value	Standard
Nominal diameter	30.0 mm	ISO 261
Coarse pitch	3.5 mm	ISO 261
Fine pitch	2.0 mm	ISO 261
Tap drill (coarse, 75% engagement)	26.5 mm	ISO 2306
Tap drill (fine)	28.0 mm	ISO 2306
Clearance hole - close	31.0 mm	ISO 273
Clearance hole - medium	33.0 mm	ISO 273
Clearance hole - coarse	36.0 mm	ISO 273
Hex head A/F (spanner size)	46.0 mm	ISO 4014
Hex head height	18.7 mm	ISO 4014
Socket head cap screw head dia	45.0 mm	ISO 4762
Socket head hex key size	22.0 mm	ISO 4762
Tensile stress area	561 mm^2	ISO 898-1
Minimum tensile strength 8.8	800 MPa	ISO 898-1
Minimum tensile strength 10.9	1040 MPa	ISO 898-1
Proof load 8.8	325.4 kN	ISO 898-1
Proof load 10.9	465.6 kN	ISO 898-1
Torque dry, class 8.8	1390 Nm	VDI 2230
Torque dry, class 10.9	1985 Nm	VDI 2230
Torque dry, class 12.9	2320 Nm	VDI 2230

M30 thread pitch

Standard M30 bolts use a 3.5 mm coarse pitch. Fine pitch M30 x 2.0 is used where vibration resistance matters or in thin-wall components. Coarse pitch is the default - if a drawing says M30 with no pitch specified, it means M30 x 3.5 coarse.

M30 tap drill size

For M30 x 3.5 coarse pitch with 75% thread engagement, drill 26.5 mm. For fine pitch, drill 28.0 mm. Smaller drills give more engagement but increase tap breakage risk without meaningful strength gain.

M30 clearance hole

For a clearance hole where the bolt passes through, use 31.0 mm (close fit), 33.0 mm (medium), or 36.0 mm (coarse) per ISO 273.

M30 torque values

Dry M30 property class 8.8: torque to 1390 Nm. Class 10.9: 1985 Nm. Class 12.9: 2320 Nm. These values target 90% proof load with K=0.20 dry thread friction. If threads are oiled or coated, reduce by 20-25%. For critical joints, always verify against the fastener manufacturer's datasheet.

M30 spanner and hex key

An M30 hex head bolt (ISO 4014) has 46.0 mm across flats, so you need a 46.0 mm spanner or socket. M30 socket head cap screws (ISO 4762) have 45.0 mm head diameter and need a 22.0 mm hex key (Allen key).

Related standards

ISO 261 - ISO general-purpose metric screw threads
ISO 273 - Fasteners: clearance holes for bolts and screws
ISO 898-1 - Mechanical properties of carbon steel fasteners
ISO 4014 - Hexagon head bolts, product grades A and B
ISO 4762 - Hexagon socket head cap screws
VDI 2230 - Systematic calculation of bolted joints

References

ISO 261:1998 - ISO metric screw threads
ISO 898-1:2013 - Mechanical properties of fasteners
VDI 2230:2015 - Calculation of bolted joints

M30 bolts and tools on Amazon

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Buy M30 hex bolts (DIN 933) on Amazon →
Buy M30 spanner (46mm) on Amazon →
Buy Torque wrench for M30 (1500Nm) on Amazon →

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Frequently Asked Questions

What is the thread pitch of an M30 bolt?

A standard M30 bolt has a coarse thread pitch of 3.5 mm per ISO 261. The fine pitch version is M30 x 2.0. If a drawing says M30 with no pitch specified, it means M30 x 3.5 coarse.

What is the tap drill size for M30?

For M30 x 3.5 coarse pitch with 75% thread engagement, drill 26.5 mm. For fine pitch, drill 28.0 mm. These values give a good balance of thread strength and tapping ease.

What torque is an M30 bolt rated for?

For a dry M30 property class 8.8 bolt, the standard torque is 1390 Nm. Class 10.9 takes 1985 Nm, class 12.9 takes 2320 Nm. Values are per VDI 2230 at 90% proof load with nut factor K=0.20. Reduce by 20-25% if threads are lubricated.

What spanner size fits an M30 bolt?

An M30 hex head bolt (ISO 4014) has a 46.0 mm across-flats (A/F) dimension, so you need a 46.0 mm spanner or socket. An M30 socket head cap screw uses a 22.0 mm hex key (Allen key).

References

Independent UK engineering trade publication. Company profiles cross-referenced with Companies House.