Threads / Size reference
M18x1.5 Metric fine
M18x1.5 has a nominal outside diameter of 18 mm and a 1.5 mm pitch.
0.708661 in
16.933333 TPI · calculated
Nominal dimensions; no class allowances or acceptance limits applied. M sizes state diameter and pitch in millimetres.
same diameter comparison
M18x1.5 vs M18x2
M18x2 Metric fine shares the nominal diameter but has a 2.000000 mm pitch. The pitch difference is 0.500000 mm; these are different nominal threads.
Swipe to compare both sizes →
| Property | M18x1.5 Metric fine | M18x2 Metric fine |
|---|---|---|
| Nominal diameter · in | 0.708661 | 0.708661 |
| Nominal diameter · mm | 18 | 18 |
| Threads per inchDifferent | 16.933333 | 12.7 |
| Pitch · mmDifferent | 1.5 | 2 |
Cutting-tap drill references
| Target theoretical thread | Listed drill | Diameter · in / mm |
|---|---|---|
| 55% | 16.90 mm | 0.665354 / 16.9 |
| 65% | 21/32 in | 0.65625 / 16.66875 |
| 75% | 16.50 mm | 0.649606 / 16.5 |
Need acceptance limits?
The complete class and applicable drawing requirements are needed. These nominal values are not maximum/minimum inspection limits.
Part has no marking?
Measure the correct diameter and pitch, then compare candidates across metric and inch systems.
Basis for this size
Nominal designation and family transcribed from the live directory on 2026-10-19; unit conversions are calculated using exactly 25.4 mm/in. The drill row was read from Guhring PDF page 2; numbered and letter drill diameters use page 1. Paid standard limit tables have not been reviewed.
ISO 261 · metric general plan ↗ · Guhring · Tap Drill Sizes ↗ Full source scope →