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M14×1.5 — Full Fastener Spec
ISO 68-1 / ISO 261 · Fine series · Tap drill, clearance hole, torque, strength and tool sizes — every number on one page.
Tap drill (75% thread)
12.5 mm
Nearest inch drill: 31/64 (0.4844") · Clearance hole (normal fit): 15.5 mm ·
8.8 torque: 152 N·m dry
Thread dimensions
Major diameter
14 mm
Pitch
1.5 mm
TPI (equivalent)
16.93
Pitch diameter
13.026 mm
Minor diameter
12.376 mm
Tensile stress area
124.55 mm²
Tap drill sizes for M14×1.5
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% | 13.026 mm | 13 mm | 0.5156" (33/64 drill) |
| 65% | 12.733 mm | 12.7 mm | 0.5000" (1/2 drill) |
| 75% | 12.539 mm | 12.5 mm | 0.4844" (31/64 drill) |
| 85% | 12.344 mm | 12.3 mm | 0.4844" (31/64 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 M14×1.5
| Fit | Hole | Use |
|---|---|---|
| Close | 15 mm | Located joints, dowel-like alignment |
| Normal | 15.5 mm | General assembly — use this unless you have a reason not to |
| Loose | 16.5 mm | Weldments, sheet stacks, tolerance build-up |
M14×1.5 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 | 58.8 N·m | 44.1 N·m | 43.4 lb-ft | 21 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 152 N·m | 114 N·m | 112 lb-ft | 54.2 kN |
| 10.9 Alloy steel, Q&T — high strength | 217 N·m | 163 N·m | 160 lb-ft | 77.5 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 254 N·m | 190 N·m | 187 lb-ft | 90.6 kN |
| A2-70 304 stainless, cold worked | 118 N·m | 88.3 N·m | 86.8 lb-ft | 42 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
21 mm or 22 mm (DIN)
Hex key (socket head)
12 mm