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M4×0.7 — Full Fastener Spec
ISO 68-1 / ISO 261 · Coarse series · Tap drill, clearance hole, torque, strength and tool sizes — every number on one page.
Tap drill (75% thread)
3.3 mm
Nearest inch drill: #30 (0.1285") · Clearance hole (normal fit): 4.5 mm ·
8.8 torque: 3.06 N·m dry
Thread dimensions
Major diameter
4 mm
Pitch
0.7 mm
TPI (equivalent)
36.29
Pitch diameter
3.545 mm
Minor diameter
3.242 mm
Tensile stress area
8.78 mm²
Tap drill sizes for M4×0.7
Percent of thread is a trade-off: 75% is the shop default because the last 25% of engagement adds only a few percent of strength while roughly doubling tapping torque. Drop to 50–65% in tough or gummy material, or for blind holes where a snapped tap means scrapping the part.
| Thread engagement | Exact | Metric drill | Nearest inch drill |
|---|---|---|---|
| 50% | 3.545 mm | 3.5 mm | 0.1360" (#29 drill) |
| 65% | 3.409 mm | 3.4 mm | 0.1360" (#29 drill) |
| 75% | 3.318 mm | 3.3 mm | 0.1285" (#30 drill) |
| 85% | 3.227 mm | 3.2 mm | 0.1250" (1/8 drill) |
Roll (form) taps need a larger hole than cut taps — add roughly
0.4× the pitch to the 75% cut-tap drill and confirm against your tap maker's chart.
Clearance hole for M4×0.7
| Fit | Hole | Use |
|---|---|---|
| Close | 4.3 mm | Located joints, dowel-like alignment |
| Normal | 4.5 mm | General assembly — use this unless you have a reason not to |
| Loose | 4.8 mm | Weldments, sheet stacks, tolerance build-up |
M4×0.7 torque specs
Calculated with the short-form equation T = K · D · F, using K = 0.2 (plain, dry, as-received steel) and a target clamp load of 75% of proof load — the standard preload target for a reusable joint.
| Grade | Dry | Lubricated | Dry (lb-ft) | Clamp load |
|---|---|---|---|---|
| 4.6 Low-carbon steel, general purpose | 1.19 N·m | 0.889 N·m | 0.874 lb-ft | 1.5 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 3.06 N·m | 2.29 N·m | 2.25 lb-ft | 3.8 kN |
| 10.9 Alloy steel, Q&T — high strength | 4.37 N·m | 3.28 N·m | 3.22 lb-ft | 5.5 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 5.11 N·m | 3.83 N·m | 3.77 lb-ft | 6.4 kN |
| A2-70 304 stainless, cold worked | 2.37 N·m | 1.78 N·m | 1.75 lb-ft | 3 kN |
The nut factor K dominates this result. Zinc-plated, waxed, anti-seize
and lubricated threads all shift K between roughly 0.10 and 0.25, which is a 2.5×
spread in torque for identical preload. If preload actually matters, torque-to-yield,
angle control or a load-indicating washer beats a torque wrench every time.
Tool sizes
Hex head wrench
7 mm
Hex key (socket head)
3 mm