Important Note
The information below is generally based on conservative appraisals of the clearance required for open ended spanners, ring spanners, and sockets. It is probable that smaller dimensions can be used if the wrench / spanner / socket geometry is selected at the early design stage. The links on this table provide more detailed information.
For Bolt edge distances applicable to structural design refer to Edge Distances
Dimensions in mm
Tables for bolts and screws in accordance with BS 3692:2001..ISO metric precision hexagon bolts, screws and nuts. Specification.
Note clearance hole dimension "D" is in line with BS EN 20273:1992, ISO 273:1979. med fit
| Size | Hole D | Min P | Clearance | G | S Nom. Size Spanner(A/F) |
H (Sq.Drive) |
||
| a | b | c | ||||||
| M3 | 3.4 | 14 | 10 | 8 | 10 | - | 5.5 | 14(6,3) |
| M4 | 4.5 | 17 | 10 | 8 | 12 | 14 | 7 | 22(10) |
| M5 | 5.5 | 20 | 10 | 8 | 12 | 14 | 8 | 22(10) |
| M6 | 6.6 | 24 | 14 | 10 | 15 | 17 | 10 | 26(12,5) |
| M8 | 9.0 | 30 | 18 | 12 | 18 | 22 | 13 | 26(12,5) |
| M10 | 11.0 | 37 | 28 | 14 | 21 | 27 | 17 | 27(12,5) |
| M12 | 13.5 | 42 | 30 | 16 | 22 | 30 | 19 | 29(12,5) |
| M16 | 17.5 | 50 | 30 | 20 | 26 | 38 | 24 | 42(20) |
| M20 | 22,0 | 60 | 32 | 22 | 32 | 46 | 30 | 47(20) |
| M24 | 26,0 | 75 | 48 | 25 | 38 | 55 | 36 | 54(20) |
| M30 | 33.0 | 94 | 60 | 30 | 48 | 70 | 46 | 70(25) |
| M36 | 39.0 | 104 | 60 | 34 | 52 | 90 | 55 | 81(25) |
High Strength Friction Grip Bolts
Dimensions in mm
Clearances suitable for bolts & nuts to BS EN 14399-3:2005.. High-strength structural bolting for preloading. System HR. Hexagon bolt and nut
| Size | Min P | Clearance | G | S Nom. Size Spanner (A/F) |
||
| a | b | c | ||||
| M16 | 56 | 30 | 25 | 38 | 27 | 27 |
| M20 | 64 | 48 | 28 | 42 | 48 | 32 |
| M24 | 84 | 48 | 40 | 55 | 65 | 41 |
| M30 | 98 | 60 | 45 | 65 | 77 | 50 |
| M36 | 112 | 60 | 45 | 70 | 81 | 60 |