Photo by Nic Wood on Pexels
Every dimension, torque value, and thread specification for the M5 metric bolt in one reference card. M5 Bolt Specifications M5 is one of the most common metric fastener sizes in UK engineering, used across small panel mounting and instrumentation.
| Property |
Value |
Standard |
| Nominal diameter |
5.0 mm |
ISO 261 |
| Coarse pitch |
0.8 mm |
ISO 261 |
| Fine pitch |
0.5 mm |
ISO 261 |
| Tap drill (coarse, 75% engagement) |
4.2 mm |
ISO 2306 |
| Tap drill (fine) |
4.5 mm |
ISO 2306 |
| Clearance hole - close |
5.3 mm |
ISO 273 |
| Clearance hole - medium |
5.5 mm |
ISO 273 |
| Clearance hole - coarse |
5.8 mm |
ISO 273 |
| Hex head A/F (spanner size) |
8.0 mm |
ISO 4014 |
| Hex head height |
3.5 mm |
ISO 4014 |
| Socket head cap screw head dia |
8.5 mm |
ISO 4762 |
| Socket head hex key size |
4.0 mm |
ISO 4762 |
| Tensile stress area |
14.2 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 |
8.2 kN |
ISO 898-1 |
| Proof load 10.9 |
11.8 kN |
ISO 898-1 |
| Torque dry, class 8.8 |
5.9 Nm |
VDI 2230 |
| Torque dry, class 10.9 |
8.4 Nm |
VDI 2230 |
| Torque dry, class 12.9 |
9.8 Nm |
VDI 2230 |
M5 thread pitch
Standard M5 bolts use a 0.8 mm coarse pitch. Fine pitch M5 x 0.5 is used where vibration resistance matters or in thin-wall components. Coarse pitch is the default - if a drawing says M5 with no pitch specified, it means M5 x 0.8 coarse.
M5 tap drill size
For M5 x 0.8 coarse pitch with 75% thread engagement, drill 4.2 mm. For fine pitch, drill 4.5 mm. Smaller drills give more engagement but increase tap breakage risk without meaningful strength gain.
M5 clearance hole
For a clearance hole where the bolt passes through, use 5.3 mm (close fit), 5.5 mm (medium), or 5.8 mm (coarse) per ISO 273.
M5 torque values
Dry M5 property class 8.8: torque to 5.9 Nm. Class 10.9: 8.4 Nm. Class 12.9: 9.8 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.
M5 spanner and hex key
An M5 hex head bolt (ISO 4014) has 8.0 mm across flats, so you need a 8.0 mm spanner or socket. M5 socket head cap screws (ISO 4762) have 8.5 mm head diameter and need a 4.0 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
M5 bolts and tools on Amazon
Shop the exact parts and tools referenced above on Amazon UK. Prices, stock, and delivery times update live; MLC earns a small commission on qualifying purchases at no cost to you.
As an Amazon Associate, MLC earns from qualifying purchases. The product links on this page support our work at no extra cost to you.
Looking for machine screw head sizes rather than bolt data? The M5 screw dimensions card covers pan, countersunk, socket cap, button and cheese heads with drive sizes and DIN vs ISO differences.
Frequently Asked Questions
What is the thread pitch of an M5 bolt?
A standard M5 bolt has a coarse thread pitch of 0.8 mm per ISO 261. The fine pitch version is M5 x 0.5. If a drawing says M5 with no pitch specified, it means M5 x 0.8 coarse.
What is the tap drill size for M5?
For M5 x 0.8 coarse pitch with 75% thread engagement, drill 4.2 mm. For fine pitch, drill 4.5 mm. These values give a good balance of thread strength and tapping ease.
What torque is an M5 bolt rated for?
For a dry M5 property class 8.8 bolt, the standard torque is 5.9 Nm. Class 10.9 takes 8.4 Nm, class 12.9 takes 9.8 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 M5 bolt?
An M5 hex head bolt (ISO 4014) has a 8.0 mm across-flats (A/F) dimension, so you need a 8.0 mm spanner or socket. An M5 socket head cap screw uses a 4.0 mm hex key (Allen key).
What are the M5 bolt dimensions?
The M5 bolt has a 5.0 mm nominal diameter and a 0.8 mm coarse pitch per ISO 261. The hex head is 8.0 mm across flats with a 3.5 mm head height per ISO 4014. The tensile stress area of an M5 thread is 14.2 mm squared per ISO 898-1, and the clearance hole ranges from 5.3 mm close to 5.8 mm coarse per ISO 273.
What is the M5 standard pitch?
The M5 standard pitch is 0.8 mm, the ISO 261 coarse pitch used by default. If a drawing specifies M5 with no pitch, it means M5 x 0.8 coarse. The fine pitch option for the M5 thread is 0.5 mm, used where vibration resistance matters or in thin-wall components.
What is the M5 bolt size in mm?
An M5 bolt has a nominal diameter of 5.0 mm, the major thread diameter measured across the outside of the thread. The M5 coarse pitch is 0.8 mm per ISO 261. The hex head measures 8.0 mm across flats per ISO 4014, so an M5 bolt takes an 8.0 mm spanner or socket.
What is the M5 clearance hole?
An M5 clearance hole, where the bolt passes straight through, is 5.3 mm for a close fit, 5.5 mm for medium, or 5.8 mm for coarse, all per ISO 273. Use the close 5.3 mm hole where alignment matters. This differs from the 4.2 mm tap drill used for a threaded M5 hole at 75 percent engagement per ISO 2306.
What is the M5 bolt diameter?
The M5 bolt diameter is 5.0 mm nominal, which is the major thread diameter per ISO 261. The default M5 coarse pitch is 0.8 mm. For a clearance hole around the 5.0 mm shank, use 5.3 mm close, 5.5 mm medium or 5.8 mm coarse per ISO 273; for a tapped thread, drill 4.2 mm.