M20 × 1.5 Tap Drill Size & Thread Specs
Everything for a M20 × 1.5 fine pitch thread on one page: tap drill (18.5 mm), clearance holes, wrench and hex key sizes, and the nearest inch thread.
SP-TD-01 · M20 × 1.5
M20 × 1.5 specs
SizePlate
M20 × 1.5 · tap with
18.5 mm drill
.7283″
18.5 mm · 77% thread
- Inch drill
- 47/64 · .7344
- Clearance
- 21 / 22 mm
- Wrench
- 30 mm
- Cap screw key
- 17 mm
Thread
- Nominal size
- M20 · .7874″
- Pitch
- 1.5 mm · 16.9 TPI
- Series
- fine
- coarse pitch
- M20 × 2.5
Drilling
- Tap drill
- 18.5 mm · .7283
- Inch substitute
- 47/64 · .7344
- Close fit
- 21 mm
- Normal fit
- 22 mm
- Free fit
- 24 mm
Tools
- Hex head (ISO 4017)
- 30 mm
- Hex head (DIN 933)
- 30 mm
- Socket head cap key
- 17 mm
- Button head key
- —
- Flat head key
- —
Nearest inch
- Thread
- 3/4-10
- Major diameter
- .7500″
- Threads per inch
- 10
- Tap drill
- 21/32
- Interchangeable
- No
Not interchangeable means the threads look close but won't run together: forcing one into the other strips both.
Drill size by thread percentage
Larger drill, less thread, easier tapping. 75% is the usual target.
| Drill | Decimal | mm | Thread |
|---|---|---|---|
| 18.5 mm | .7283 | 18.5 | 77% |
| 47/64 | .7344 | 18.65 | 69% |
| 19 mm | .7480 | 19 | 51% |
| 3/4 | .7500 | 19.05 | 49% |
Neighboring sizes
Questions
What does M20 × 1.5 mean?
An ISO metric thread with a 20 mm major diameter and a 1.5 mm pitch (the distance from one thread crest to the next). It’s the fine pitch for M20.
Can I use a 47/64 drill instead?
Usually. 47/64 is .7344″ against .7283″ for the 18.5 mm drill, which changes the thread engagement by a few percent at most.