M10 Bolt - 1.5 mm Pitch, 8.5 mm Tap Drill, 49 Nm Torque
Verified by Rachel Mayfield, Supply Chain Analyst - April 2026
Complete M10 metric bolt reference: thread pitch, tap drill size, clearance holes, spanner and hex key sizes, torque values for all property classes, and proof loads. M10 Bolt Specifications M10 is the most common size for structural fasteners, engine mounts, and medium-duty machinery assemblies in UK engineering.
| Property | Value | Standard |
|---|---|---|
| Nominal diameter | 10.0 mm | ISO 261 |
| Coarse pitch | 1.5 mm | ISO 261 |
| Fine pitch | 1.25 mm / 1.0 mm | ISO 261 |
| Tap drill (coarse, 75% engagement) | 8.5 mm | ISO 2306 |
| Tap drill (fine 1.25) | 8.75 mm | ISO 2306 |
| Clearance hole - close | 10.5 mm | ISO 273 |
| Clearance hole - medium | 11.0 mm | ISO 273 |
| Clearance hole - coarse | 12.0 mm | ISO 273 |
| Hex head A/F (spanner size) | 16.0 mm | ISO 4014 |
| Hex head height | 6.4 mm | ISO 4014 |
| Socket head cap screw head dia | 16.0 mm | ISO 4762 |
| Socket head hex key size | 8.0 mm | ISO 4762 |
| Tensile stress area | 58.0 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 | 32.5 kN | ISO 898-1 |
| Proof load 10.9 | 46.4 kN | ISO 898-1 |
| Torque dry, class 8.8 | 49 Nm | VDI 2230 |
| Torque dry, class 10.9 | 69 Nm | VDI 2230 |
| Torque dry, class 12.9 | 81 Nm | VDI 2230 |
M10 thread pitch
Standard M10 uses a 1.5 mm coarse pitch. Two fine pitch options exist: M10 x 1.25 and M10 x 1.0. Fine pitch improves vibration resistance and allows thinner wall sections, but requires a larger tap drill because the thread depth is smaller.
M10 tap drill and clearance hole
Drill 8.5 mm for M10 x 1.5 coarse with 75% thread engagement. For a clearance hole where the bolt passes through, use 10.5 mm (close fit), 11 mm (medium), or 12 mm (coarse) per ISO 273.
M10 torque values
Dry M10 property class 8.8: torque to 49 Nm. Class 10.9: 69 Nm. Class 12.9: 81 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.
M10 spanner and hex key
An M10 hex head bolt (ISO 4014) has 16 mm across flats, so you need a 16 mm spanner or socket. M10 socket head cap screws (ISO 4762) have 16 mm head diameter and need an 8 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
Frequently Asked Questions
What is the thread pitch of an M10 bolt?
Standard M10 coarse pitch is 1.5 mm per ISO 261. Fine pitch options are M10 x 1.25 or M10 x 1.0 for applications needing better vibration resistance or thinner wall sections.
What is the tap drill size for M10?
For M10 x 1.5 coarse pitch, drill 8.5 mm for approximately 75% thread engagement. For M10 x 1.25 fine, drill 8.75 mm. For M10 x 1.0 fine, drill 9.0 mm.
What torque should I apply to an M10 8.8 bolt?
A dry M10 property class 8.8 bolt should be torqued to 49 Nm. Class 10.9 takes 69 Nm, class 12.9 takes 81 Nm. These are per VDI 2230 at 90% proof load with K=0.20. Reduce by 20-25% if threads are lubricated.
What size spanner fits an M10 bolt?
An M10 hex head bolt needs a 16 mm spanner or socket (A/F dimension per ISO 4014). An M10 socket head cap screw needs an 8 mm hex key (Allen key).
What does M10 Bolt - 1.5 mm Pitch, 8.5 mm Tap Drill, 49 Nm Torque refer to?
It refers to a metric bolt with a nominal diameter of 10.0 mm and a coarse pitch of 1.5 mm according to ISO 261 standards.
What are the main types or variants of M10 Bolts available in UK engineering, specifically for the variant mentioned?
The main type is the coarse pitch variant with a tap drill size of 8.5 mm as per ISO 2306, and there's also a fine pitch option with a tap drill size of 8.75 mm.
How should one choose between different property classes for an M10 Bolt - 1.5 mm Pitch, 8.5 mm Tap Drill?
Choosing the correct property class depends on the application's strength requirements and environmental conditions. For example, a higher property class like 12 would be chosen for high-stress applications requiring greater tensile strength.
Which standards apply to M10 Bolt - 1.5 mm Pitch, 8.5 mm Tap Drill when selecting materials and dimensions?
The relevant standards include ISO 261 for thread pitch, ISO 2306 for tap drill sizes, and ISO 4014 for hex head dimensions.
Where can UK engineers find reliable suppliers of M10 Bolt - 1.5 mm Pitch, 8.5 mm Tap Drill?
Reliable UK suppliers include companies like Fastenal, Bremick Engineering Supplies, and RS Components that stock a wide range of metric bolts adhering to the specified standards.
What is the typical cost or availability status for M10 Bolt - 1.5 mm Pitch, 8.5 mm Tap Drill in the UK market?
The cost varies based on quantity and supplier but generally ranges from £0.20 to £0.60 per bolt. Availability is typically high due to its common use in engineering applications.