M3 × 0.5 Tap Drill Size & Thread Specs
Everything for a M3 × 0.5 coarse pitch thread on one page: tap drill (2.5 mm), clearance holes, wrench and hex key sizes, and the nearest inch thread.
SP-TD-01 · M3 × 0.5
M3 × 0.5 specs
SizePlate
M3 × 0.5 · tap with
2.5 mm drill
.0984″
2.5 mm · 77% thread
- Inch drill
- #40 · .0980
- Clearance
- 3.2 / 3.4 mm
- Wrench
- 5.5 mm
- Cap screw key
- 2.5 mm
Thread
- Nominal size
- M3 · .1181″
- Pitch
- 0.5 mm · 50.8 TPI
- Series
- coarse
- fine pitch
- M3 × 0.35
Drilling
- Tap drill
- 2.5 mm · .0984
- Inch substitute
- #40 · .0980
- Close fit
- 3.2 mm
- Normal fit
- 3.4 mm
- Free fit
- 3.6 mm
Tools
- Hex head (ISO 4017)
- 5.5 mm
- Hex head (DIN 933)
- 5.5 mm
- Socket head cap key
- 2.5 mm
- Button head key
- 2 mm
- Flat head key
- 2 mm
Nearest inch
- Thread
- #4-40
- Major diameter
- .1120″
- Threads per inch
- 40
- Tap drill
- #43
- 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 |
|---|---|---|---|
| #40 | .0980 | 2.49 | 79% |
| 2.5 mm | .0984 | 2.5 | 77% |
| #39 | .0995 | 2.53 | 73% |
| #38 | .1015 | 2.58 | 65% |
| 2.6 mm | .1024 | 2.6 | 62% |
| #37 | .1040 | 2.64 | 55% |
| 2.65 mm | .1043 | 2.65 | 54% |
| 2.7 mm | .1063 | 2.7 | 46% |
| #36 | .1065 | 2.71 | 45% |
Neighboring sizes
- M1.6 × 0.35tap 1.25 mm
- M2 × 0.4tap 1.6 mm
- M2.5 × 0.45tap 2.05 mm
- M3 × 0.35tap 2.65 mm
- M4 × 0.7tap 3.3 mm
- M4 × 0.5tap 3.5 mm
Questions
What does M3 × 0.5 mean?
An ISO metric thread with a 3 mm major diameter and a 0.5 mm pitch (the distance from one thread crest to the next). It’s the coarse pitch for M3.
Can I use a #40 drill instead?
Usually. #40 is .0980″ against .0984″ for the 2.5 mm drill, which changes the thread engagement by a few percent at most.