Thread series · Metric coarse
ISO Metric Coarse Thread Chart — All Sizes, Dimensions & Tap Drills
https://shopmath.org/threads/metric-coarse · data verified August 1, 2026
The ISO Metric Coarse series covers 31 standard sizes, from M1.6×0.35 to M64×6, and 31 of them carry a tap drill recommendation. ISO 261 coarse metric threads — the default pitch for each nominal diameter.
- Sizes
- 31
- Smallest
- M1.6×0.35
- Largest
- M64×6
- Standard
- ISO 68-1, ISO 261, ISO 262, ISO 965-1, ISO 898-1
Every Metric coarse Thread Size — Dimensions and Tap Drills
31 sizes, ordered smallest to largest. Every row links to the full page for that thread, with class limits, clearance holes and tap drills across 50–85% engagement.
| Property | Property | Major Ø | Pitch Ø | Minor Ø | Tap drill | |||||
|---|---|---|---|---|---|---|---|---|---|---|
| Thread | Pitch mm | in | mm | in | mm | in | mm | Drill | in | mm |
| M1.6×0.35 | 0.350 | 0.0630 | 1.600 | 0.0541 | 1.373 | 0.0481 | 1.221 | 1.25 mm | 0.0492 | 1.250 |
| M1.8×0.35 | 0.350 | 0.0709 | 1.800 | 0.0619 | 1.573 | 0.0559 | 1.421 | 1.45 mm | 0.0571 | 1.450 |
| M2×0.4 | 0.400 | 0.0787 | 2.000 | 0.0685 | 1.740 | 0.0617 | 1.567 | 1.6 mm | 0.0630 | 1.600 |
| M2.5×0.45 | 0.450 | 0.0984 | 2.500 | 0.0869 | 2.208 | 0.0793 | 2.013 | 2.05 mm | 0.0807 | 2.050 |
| M3×0.5 | 0.500 | 0.1181 | 3.000 | 0.1053 | 2.675 | 0.0968 | 2.459 | 2.5 mm | 0.0984 | 2.500 |
| M3.5×0.6 | 0.600 | 0.1378 | 3.500 | 0.1224 | 3.110 | 0.1122 | 2.850 | 2.9 mm | 0.1142 | 2.900 |
| M4×0.7 | 0.700 | 0.1575 | 4.000 | 0.1396 | 3.545 | 0.1276 | 3.242 | 3.3 mm | 0.1299 | 3.300 |
| M5×0.8 | 0.800 | 0.1968 | 5.000 | 0.1764 | 4.480 | 0.1628 | 4.134 | 4.2 mm | 0.1653 | 4.200 |
| M6×1 | 1.000 | 0.2362 | 6.000 | 0.2106 | 5.350 | 0.1936 | 4.917 | 5 mm | 0.1968 | 5.000 |
| M7×1 | 1.000 | 0.2756 | 7.000 | 0.2500 | 6.350 | 0.2329 | 5.917 | 6 mm | 0.2362 | 6.000 |
| M8×1.25 | 1.250 | 0.3150 | 8.000 | 0.2830 | 7.188 | 0.2617 | 6.647 | 6.8 mm | 0.2677 | 6.800 |
| M10×1.5 | 1.500 | 0.3937 | 10.000 | 0.3553 | 9.026 | 0.3298 | 8.376 | 8.5 mm | 0.3347 | 8.500 |
| M12×1.75 | 1.750 | 0.4724 | 12.000 | 0.4277 | 10.863 | 0.3979 | 10.106 | 10.3 mm | 0.4055 | 10.300 |
| M14×2 | 2.000 | 0.5512 | 14.000 | 0.5000 | 12.701 | 0.4659 | 11.835 | 12.1 mm | 0.4764 | 12.100 |
| M16×2 | 2.000 | 0.6299 | 16.000 | 0.5788 | 14.701 | 0.5447 | 13.835 | 14 mm | 0.5512 | 14.000 |
| M18×2.5 | 2.500 | 0.7087 | 18.000 | 0.6447 | 16.376 | 0.6021 | 15.294 | 15.5 mm | 0.6102 | 15.500 |
| M20×2.5 | 2.500 | 0.7874 | 20.000 | 0.7235 | 18.376 | 0.6809 | 17.294 | 17.5 mm | 0.6890 | 17.500 |
| M22×2.5 | 2.500 | 0.8661 | 22.000 | 0.8022 | 20.376 | 0.7596 | 19.294 | 19.5 mm | 0.7677 | 19.500 |
| M24×3 | 3.000 | 0.9449 | 24.000 | 0.8681 | 22.051 | 0.8170 | 20.752 | 21 mm | 0.8268 | 21.000 |
| M27×3 | 3.000 | 1.0630 | 27.000 | 0.9863 | 25.051 | 0.9351 | 23.752 | 24 mm | 0.9449 | 24.000 |
| M30×3.5 | 3.500 | 1.1811 | 30.000 | 1.0916 | 27.727 | 1.0319 | 26.211 | 25 mm | 0.9842 | 25.000 |
| M33×3.5 | 3.500 | 1.2992 | 33.000 | 1.2097 | 30.727 | 1.1500 | 29.211 | 25 mm | 0.9842 | 25.000 |
| M36×4 | 4.000 | 1.4173 | 36.000 | 1.3150 | 33.402 | 1.2469 | 31.670 | 25 mm | 0.9842 | 25.000 |
| M39×4 | 4.000 | 1.5354 | 39.000 | 1.4331 | 36.402 | 1.3650 | 34.670 | 25 mm | 0.9842 | 25.000 |
| M42×4.5 | 4.500 | 1.6535 | 42.000 | 1.5385 | 39.077 | 1.4618 | 37.129 | 25 mm | 0.9842 | 25.000 |
| M45×4.5 | 4.500 | 1.7716 | 45.000 | 1.6566 | 42.077 | 1.5799 | 40.129 | 25 mm | 0.9842 | 25.000 |
| M48×5 | 5.000 | 1.8898 | 48.000 | 1.7619 | 44.752 | 1.6766 | 42.587 | 25 mm | 0.9842 | 25.000 |
| M52×5 | 5.000 | 2.0472 | 52.000 | 1.9194 | 48.752 | 1.8341 | 46.587 | 25 mm | 0.9842 | 25.000 |
| M56×5.5 | 5.500 | 2.2047 | 56.000 | 2.0641 | 52.428 | 1.9703 | 50.046 | 25 mm | 0.9842 | 25.000 |
| M60×5.5 | 5.500 | 2.3622 | 60.000 | 2.2216 | 56.428 | 2.1278 | 54.046 | 25 mm | 0.9842 | 25.000 |
| M64×6 | 6.000 | 2.5197 | 64.000 | 2.3663 | 60.103 | 2.2640 | 57.505 | 25 mm | 0.9842 | 25.000 |
Basic dimensions are the theoretical values before a tolerance class is applied. Tap drills are for cut taps at the default engagement; per-size pages carry 50–85%.
Sources and Method for the Metric coarse Thread Chart
- Metric coarse thread dimensionscomputed+compiled
ISO 68-1 basic profile and ISO 898-1 tensile stress area; verified in docs/research/data-sourcing.md §3.2; diameter/pitch pairs: ISO 261 / ISO 262 diameter-pitch pairs via Wikipedia (CC BY-SA 4.0); cross-checked against threadlib metric_thread.csv (BSD-3) and FreeCAD CAM metric-internal-6H.csv (LGPL-2.1+); clearance holes: ISO 273 (metric) and ASME B18.2.8 (inch) via FreeCAD FeatureHole.cpp (LGPL-2.1+), cross-checked against bd_warehouse clearance_hole_sizes.csv (Apache-2.0)
Verified against threadlib metric_thread.csv (BSD-3-Clause) and FreeCAD CAM metric-internal-6H.csv (LGPL-2.1+), agreeing cell-for-cell — 215 checks passed at 0.001 mm
Part computed from the standard's formulas, part compiled from agreeing public sources.
- Assumptions
- Tap drill figures are for cut taps at the default thread engagement; each size page carries the full 50–85% range.
- Dataset scope: EXCLUDED: ISO 965-1 tolerance-grade formulas (not located — data-sourcing.md open item 2), 6g external limits (single-sourced), form tap drills, M68-M100 (verified demand cliff at M64).
- Data last verified
- August 1, 2026
How to Cite This Metric coarse Thread Chart
Citation
ShopMath. "ISO Metric Coarse Thread Chart — All Sizes, Dimensions & Tap Drills." ShopMath, verified August 1, 2026, https://shopmath.org/threads/metric-coarse
BibTeX
@misc{shopmath-threads-metric-coarse,
title = {ISO Metric Coarse Thread Chart — All Sizes, Dimensions & Tap Drills},
author = {{ShopMath}},
year = {2026},
howpublished = {\url{https://shopmath.org/threads/metric-coarse}},
note = {Data verified 2026-08-01}
}Permanent URL
https://shopmath.org/threads/metric-coarse