Metric tap drill size chart
Tap drill finder
Choose the thread and the material. We'll show the drill, the tap and the lubricant, and the exact sizes we stock.
Answer
| Thread | Pitch (mm) | Tap drill (mm) |
|---|---|---|
| M3 | 0.5 | 2.5 |
| M4 | 0.7 | 3.3 |
| M5 | 0.8 | 4.2 |
| M6 | 1.0 | 5.0 |
| M8 | 1.25 | 6.8 |
| M10 | 1.5 | 8.5 |
| M12 | 1.75 | 10.2 |
| M14 | 2.0 | 12.0 |
| M16 | 2.0 | 14.0 |
| M18 | 2.5 | 15.5 |
| M20 | 2.5 | 17.5 |
| M24 | 3.0 | 21.0 |
Metric tap drill chart
Standard tap drills for metric coarse and fine threads, for about 75% thread depth. For hard or critical work, check your tool maker's data.
| Thread | Pitch (mm) | Tap drill (mm) |
|---|---|---|
| M1.6 | 0.35 | 1.25 |
| M2 | 0.4 | 1.6 |
| M2.5 | 0.45 | 2.05 |
| M3 | 0.5 | 2.5 |
| M4 | 0.7 | 3.3 |
| M5 | 0.8 | 4.2 |
| M6 | 1.0 | 5.0 |
| M8 | 1.25 | 6.8 |
| M10 | 1.5 | 8.5 |
| M12 | 1.75 | 10.2 |
| M14 | 2.0 | 12.0 |
| M16 | 2.0 | 14.0 |
| M18 | 2.5 | 15.5 |
| M20 | 2.5 | 17.5 |
| M22 | 2.5 | 19.5 |
| M24 | 3.0 | 21.0 |
| M27 | 3.0 | 24.0 |
| M30 | 3.5 | 26.5 |
| Thread | Pitch (mm) | Tap drill (mm) |
|---|---|---|
| M5 × 0.5 | 0.5 | 4.5 |
| M6 × 0.75 | 0.75 | 5.2 |
| M8 × 1.0 | 1.0 | 7.0 |
| M8 × 0.75 | 0.75 | 7.2 |
| M10 × 1.25 | 1.25 | 8.8 |
| M10 × 1.0 | 1.0 | 9.0 |
| M12 × 1.5 | 1.5 | 10.5 |
| M12 × 1.25 | 1.25 | 10.8 |
| M14 × 1.5 | 1.5 | 12.5 |
| M16 × 1.5 | 1.5 | 14.5 |
| M18 × 2.0 | 2.0 | 16.0 |
| M18 × 1.5 | 1.5 | 16.5 |
| M20 × 2.0 | 2.0 | 18.0 |
| M20 × 1.5 | 1.5 | 18.5 |
| M22 × 2.0 | 2.0 | 20.0 |
| M22 × 1.5 | 1.5 | 20.5 |
| M24 × 2.0 | 2.0 | 22.0 |
| M24 × 1.5 | 1.5 | 22.5 |
| M27 × 2.0 | 2.0 | 25.0 |
| M30 × 2.0 | 2.0 | 28.0 |
Common questions
How do I work out a metric tap drill size?
Take the pitch away from the thread diameter. An M8 thread has a 1.25 mm pitch, so 8 - 1.25 = 6.75, and the standard drill is 6.8 mm. This gives about 75% thread depth, which is right for most work.
What size drill for an M6 tap?
5.0 mm for a standard M6 x 1.0 coarse thread, and 5.2 mm for M6 x 0.75 fine.
What size drill for an M10 tap?
8.5 mm for M10 x 1.5 coarse, 8.8 mm for M10 x 1.25 fine and 9.0 mm for M10 x 1.0 fine.
How deep should I drill a blind hole before tapping?
Drill at least three thread pitches deeper than the thread you need, so the tap's lead has room and the chips have somewhere to go. Use a bottoming or spiral flute tap to thread close to the bottom.
Which tap should I use?
By hand in a through hole, a taper tap. By hand in a blind hole, a set of three: taper, second and bottoming. On a machine, a spiral point tap for through holes and a spiral flute tap for blind holes.