Metric coarse
Tap drill 0.95 mm for a M1.2 × 0.25 thread - major Ø 1.2 mm, pitch 0.25 mm (≈101.6 TPI (converted)).
Profile
| Designation | M1.2 × 0.25 |
|---|---|
| Major (outside) diameter | 1.2 mm · 0.0472" |
| Pitch | 0.25 mm · ≈101.6 TPI (converted) |
| Pitch diameter | 1.038 mm · 0.0409" |
| Minor diameter (external) | 0.893 mm · 0.0352" |
| Minor diameter (internal) | 0.929 mm · 0.0366" |
| Recommended tap drill | 0.95 mm · ≈77% thread |
| Clearance hole | Close 1.3 · Normal 1.4 · Loose 1.5 mm |
ISO 273 clearance holes (fine / medium / coarse).
M1.2 × 0.25 is 1.2 mm across the crests with a 0.25 mm pitch, which is 101.6 threads per inch. The basic pitch diameter is 1.038 mm and the bolt's minor diameter 0.893 mm, so the thread is 0.153 mm deep on the bolt. The nearest inch size, #0-80 UNF, is 0.32 mm larger across the crests and its pitch is 0.068 mm coarser, so the two do not interchange.
Hole = D − % × 0.0129904 × P, with D = 1.2 mm and P = 0.25 mm. A smaller hole leaves more thread; the recommended 0.95 mm drill above gives about 77%.
| Thread | Hole (mm) | Hole (in) |
|---|---|---|
| 60% | 1.01 | 0.0396 |
| 65% | 0.99 | 0.0389 |
| 70% | 0.97 | 0.0383 |
| 75% | 0.96 | 0.0377 |
ISO 898-1 specifies property classes from M1.6 upwards, so no proof load or tightening torque is published for this size.
The bolt schedule collects the fasteners for one job onto a single sheet - tap drill, wrench size, grade and tightening torque on every line, taken straight from pages like this one. Free schedules hold 3 lines and are saved in this browser only.
For a M1.2 × 0.25 thread, drill the hole with a 0.95 mm tap drill (0.95 mm - the standard D − P rule) before tapping. That produces roughly 77% thread engagement, the usual target for a strong, tappable hole. The mating bolt has a major diameter of 1.2 mm and a pitch of 0.25 mm (≈101.6 TPI (converted)).
To pass a M1.2 × 0.25 bolt through a part rather than thread it, use a clearance hole: Close 1.3 · Normal 1.4 · Loose 1.5 mm.
All values come from the standard thread formulas (ISO 68-1 / ASME B1.1) and published standard tables. See the full reference.
Drill 0.95 mm before tapping M1.2 × 0.25. That leaves roughly 77% thread engagement, the usual target for a strong hole that still taps cleanly.
M1.2 × 0.25 is a metric coarse thread. Coarse is the default pitch for M1.2: when a drawing or supplier says just M1.2, it means this 0.25 mm pitch.
Drill 1.3 mm for a close fit, 1.4 mm for a normal fit or 1.5 mm for a loose fit (ISO 273). A clearance hole lets the M1.2 × 0.25 bolt pass through the part instead of threading into it.
The pitch diameter of M1.2 × 0.25 is 1.038 mm (0.0409"). It is the diameter where the thread ridge and groove are equally wide, and the reference dimension for checking thread fit.
Closest inch sizes
Nearest standard Unified sizes by major diameter. These are substitutes by size only - the thread forms are not interchangeable, so never run one into the other.
Nearby sizes