M36 × 3 tap drill size
The tap drill for M36×3 fine is 33 mm. That’s the standard chart size and gives about 77% of full thread.
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Tap drill by thread percentage
75% is the usual workshop figure. Less thread is easier to tap; more adds little strength.
| Thread % | Ideal drill | Nearest metric drill | Nearest imperial drill |
|---|---|---|---|
| 60% | 33.662 mm 1.3253" | 33.75 mm (58%) | 1-21/64" 1.3281" (58%) |
| 65% | 33.467 mm 1.3176" | 33.5 mm (64%) | 1-5/16" 1.3125" (68%) |
| 70% | 33.272 mm 1.3099" | 33.25 mm (71%) | 1-5/16" 1.3125" (68%) |
| 75% | 33.077 mm 1.3023" | 33 mm (77%) | 1-19/64" 1.2969" (79%) |
| 80% | 32.882 mm 1.2946" | 33 mm (77%) | 1-19/64" 1.2969" (79%) |
About this size
Fine-pitch metric threads are used where you need more strength in thin walls, finer adjustment or better resistance to vibration, for example on hydraulic and automotive parts. The pitch must be written in full (M10 × 1.25); without it, M10 means coarse.
- For stainless steel, duplex and other tough materials, go to about 65% thread: a 33.5 mm drill gives 64%. For mild steel, brass and cast iron the 33 mm is fine.
- At this size many people bore the hole and screwcut the thread on the lathe instead of using a hand tap. See the thread calculator for depths and the infeed.
- For a blind hole with 1.5 × D thread engagement (54 mm), drill about 66 mm deep. That leaves room for the 3–4 tapered lead threads on a second or plug tap. In steel, 1 × D engagement is usually enough; in aluminium or cast iron allow 1.5–2 × D.
Clearance holes for M36 × 3
| Fit | Drill |
|---|---|
| Close | 37 mm (1.457") |
| Medium (normal) | 39 mm (1.535") |
| Free (loose) | 42 mm (1.654") |
Fine, medium and coarse series from ISO 273. Medium suits most jobs; use fine where parts must locate closely and coarse for quick assembly or coated bolts.
M36 × 3 thread data
| Designation | M36×3 fine |
|---|---|
| Standard | ISO 68-1 basic profile, ISO 261/262 series |
| Pitch | 3 mm pitch (8.5 TPI equivalent) |
| Thread angle | 60° |
| Major diameter | 36 mm (1.417") |
| Pitch (effective) diameter | 34.051 mm (1.341") |
| Minor diameter, external | 32.319 mm (1.272") |
| Minor diameter, internal | 32.752 mm (1.289") |
| Thread depth (internal) | 1.624 mm |
Basic sizes. Real screws are slightly under and real nuts slightly over these values because of tolerance classes.
Quick calculator
Nearest alternatives
If you don’t have the right drill, these give:
- 32.75 mm drill → about 83% thread
- 33 mm drill → about 77% thread
- 33.25 mm drill → about 71% thread
Other pitches of M36: M36 coarse.
Threads close in size (not interchangeable – the pitch and/or angle differ):
- M36 – 36 mm major, 4 mm pitch (6.3 TPI equivalent)
- G1 (1" BSP) – 33.25 mm major, 11 TPI (2.309 mm pitch)
- M33 – 33 mm major, 3.5 mm pitch (7.3 TPI equivalent)
Questions
What size drill for a M36 × 3 tap?
The tap drill for M36×3 fine is 33 mm. That’s the standard chart size and gives about 77% of full thread.
What size clearance hole for M36 × 3?
For a M36 × 3 screw or bolt, drill 37 mm for a close fit, 39 mm for a medium (normal) fit or 42 mm for a free fit. These are the ISO 273 fine, medium and coarse sizes.
What is the pitch of M36 × 3?
M36×3 fine has a 3 mm pitch (8.5 TPI equivalent), a 60° thread angle and a 36 mm major diameter.
Sources: Chart drill: the usual fine-pitch rule, drill = D − P. Percent values from the ISO 68-1 basic profile. Clearance holes: ISO 273 (checked 25/10/2026). Values are for reference only – check your tap maker’s chart. See the disclaimer.
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