M16 x 1.5 thread pitch and dimensions
M16 x 1.5 is an M16 fine thread with a 1.5 mm pitch (ISO 261), about 16.9 threads per inch. Its basic pitch diameter is 15.026 mm and its minor diameter is 14.376 mm in the nut and 14.160 mm on the bolt (ISO 724 / ISO 898-1).
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| Dimension | Formula | mm | inch |
|---|---|---|---|
| Major diameter d | nominal | 16.000 | 0.6299 |
| Pitch P | ISO 261 | 1.500 | 0.0591 |
| Pitch diameter d2 | d − 0.649519 P | 15.026 | 0.5916 |
| Minor diameter D1 (nut) | d − 1.082532 P | 14.376 | 0.5660 |
| Minor diameter d3 (bolt) | d − 1.226869 P | 14.160 | 0.5575 |
| Fundamental triangle H | 0.866025 P | 1.299 | 0.0511 |
| Thread overlap H1 | 0.541266 P | 0.812 | 0.0320 |
| Thread | Pitch | Series | Pitch Ø d2 | Stress area As | Tap drill |
|---|---|---|---|---|---|
| M16 x 2.0 | 2.0 mm | coarse | 14.701 mm | 157 mm² | 14.0 mm |
| M16 x 1.5 (this page) | 1.5 mm | fine | 15.026 mm | 167 mm² | 14.5 mm |
| Thread | Pitch | Minor Ø nut D1 | Stress area As | Hex AF |
|---|---|---|---|---|
| M12 x 1.25 | 1.25 mm | 10.647 mm | 92.1 mm² | 18.0 mm |
| M14 x 1.5 | 1.5 mm | 12.376 mm | 125 mm² | 21.0 mm |
| M16 x 1.5 (this page) | 1.5 mm | 14.376 mm | 167 mm² | 24.0 mm |
| M18 x 1.5 | 1.5 mm | 16.376 mm | 216 mm² | 27.0 mm |
| M20 x 1.5 | 1.5 mm | 18.376 mm | 272 mm² | 30.0 mm |
Practical notes
Metric threads are named by major diameter and pitch: M16 x 1.5 means a 16 mm nominal diameter with 1.5 mm between crests. Because it is not the coarse pitch, the pitch must always be written, e.g. "M16 x 1.5".
The pitch diameter and minor diameters above are basic (zero-tolerance) sizes. Real nuts and bolts are made to a tolerance class, usually 6H for the nut and 6g for the bolt (ISO 965), so a measured bolt is slightly under these values.
To identify a thread, measure the major diameter with calipers and the pitch with a thread gauge, or count crests over 10 mm. M16 x 1.5 has about 16.9 threads per inch, which is close to, but not the same as, any Unified thread; an inch nut will not run on it.
Tensile stress area As is what bolt strength is calculated on (proof load = As × proof stress for the property class in ISO 898-1). For M16 x 1.5 it is 167 mm².
FAQ
What is the pitch of an M16 x 1.5 thread?
M16 x 1.5 has a 1.5 mm pitch, a fine pitch in ISO 261. The coarse pitch for M16 is 2.0 mm.
What is the minor diameter of M16 x 1.5?
The basic minor diameter is 14.376 mm for the internal thread (nut, D1 = d − 1.082532 P) and 14.160 mm for the external thread (bolt, d3 = d − 1.226869 P).
What is the tensile stress area of M16 x 1.5?
As = π/4 × ((d2 + d3)/2)² = 167 mm² for M16 x 1.5 (ISO 898-1).
What tap drill does M16 x 1.5 need?
14.5 mm for a cut tap (major diameter minus pitch, ISO 2306), which gives about 77% thread.
What spanner size fits an M16 x 1.5 bolt?
ISO 4032 nuts and ISO 4014/4017 bolts in M16 x 1.5 are 24.0 mm across flats. Older DIN 934/933 parts can differ at M10, M12, M14 and M22.
Sources: ISO 261 — ISO general purpose metric screw threads, general plan (pitch series) · ISO 724 — ISO general purpose metric screw threads, basic dimensions · ISO 898-1 — mechanical properties of fasteners (minor diameter d3, tensile stress area As) · ISO 4032 / ISO 4014 — hexagon nuts and bolts (width across flats)
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