M8 × 1 Thread
The chart recommendation gives approximately 77% thread engagement — the conventional target for average materials. It is not the only valid choice; see the options below.
Specification
| Designation | M8 × 1 |
|---|---|
| Thread family | ISO metric fine |
| Nominal size | M8 |
| Basic major diameter | 0.3150″ / 8 mm |
| Pitch | 1 mm |
| Recommended tap drill | 7 mm (0.2756″ / 7 mm) |
Tap drill options by thread engagement
Any of these standard drills produces a usable engagement for M8 × 1; smaller drills give stronger threads but higher tapping torque. Percentages use the conventional approximation (60° thread form).
| Drill | Decimal in | mm | Approx. engagement |
|---|---|---|---|
| 6.9 mm | 0.2717 | 6.9 | 84.7% |
| I | 0.2720 | 6.909 | 84% |
| 7 mm — chart recommendation | 0.2756 | 7 | 77% |
| J | 0.2770 | 7.036 | 74.2% |
| 7.1 mm | 0.2795 | 7.1 | 69.3% |
| K | 0.2810 | 7.137 | 66.4% |
| 9/32″ | 0.2813 | 7.144 | 65.9% |
| 7.2 mm | 0.2835 | 7.2 | 61.6% |
Nearest drills to the tap drill in other systems
| Drill | Size | vs 7 mm | Resulting engagement |
|---|---|---|---|
| 9/32″ | 0.2813″ / 7.144 mm | +0.144 mm | 65.9% |
| J | 0.2770″ / 7.036 mm | +0.036 mm | 74.2% |
Clearance holes
For a bolt or screw of this size to pass through freely. ISO 273 series (fine/medium/coarse), shown as close, normal, and loose.
Hex bolt & nut dimensions
For a standard hex bolt (ISO 4014/4017) and style-1 nut (ISO 4032) in this size.
| Wrench / socket size (bolt head) | 13 mm |
|---|---|
| Head height | 5.3 mm |
| Nut thickness | 6.8 mm |
| Compatible nut | M8 × 1 hex nut |
Basic (nominal) dimensions. See the wrench & socket size charts for all sizes and the metric ↔ SAE socket comparison.
Related threads
- M8 × 1.25 — same nominal size, 1.25 mm pitch (ISO metric coarse) · compare
- M10 × 1 — next size up in metric-fine