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M22×1.5 — 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)
20.5 mm
Nearest inch drill: 13/16 (0.8125") · Clearance hole (normal fit): 24 mm ·
8.8 torque: 637 N·m dry
Thread dimensions
Major diameter
22 mm
Pitch
1.5 mm
TPI (equivalent)
16.93
Pitch diameter
21.026 mm
Minor diameter
20.376 mm
Tensile stress area
333.06 mm²
Tap drill sizes for M22×1.5
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% | 21.026 mm | 21 mm | 0.8281" (53/64 drill) |
| 65% | 20.733 mm | 20.7 mm | 0.8125" (13/16 drill) |
| 75% | 20.539 mm | 20.5 mm | 0.8125" (13/16 drill) |
| 85% | 20.344 mm | 20.3 mm | 0.7969" (51/64 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 M22×1.5
| Fit | Hole | Use |
|---|---|---|
| Close | 23 mm | Located joints, dowel-like alignment |
| Normal | 24 mm | General assembly — use this unless you have a reason not to |
| Loose | 26 mm | Weldments, sheet stacks, tolerance build-up |
M22×1.5 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 | 247 N·m | 185 N·m | 182 lb-ft | 56.2 kN |
| 8.8 Medium-carbon, quenched & tempered — the default structural grade | 637 N·m | 478 N·m | 470 lb-ft | 144.9 kN |
| 10.9 Alloy steel, Q&T — high strength | 912 N·m | 684 N·m | 673 lb-ft | 207.3 kN |
| 12.9 Alloy steel, Q&T — highest common grade (socket head cap screws) | 1066 N·m | 800 N·m | 786 lb-ft | 242.3 kN |
| A2-70 304 stainless, cold worked | 495 N·m | 371 N·m | 365 lb-ft | 112.4 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
34 mm or 32 mm (DIN)
Hex key (socket head)
17 mm