Tap drill size chart in mm for metric coarse and fine threads
The drill to use before tapping each metric thread, coarse and fine, with the limits of the nut minor diameter in class 6H that the drilled hole has to respect.
Tap drill for a thread
Tap drill size chart in mm, coarse thread
| Thread | Drillmm | D1 min6H, mm | D1 max6H, mm |
|---|---|---|---|
| M1 | 0.75 | 0.729 | – |
| M1.1 | 0.85 | 0.829 | – |
| M1.2 | 0.95 | 0.929 | – |
| M1.4 | 1.1 | – | – |
| M1.6 | 1.25 | 1.221 | 1.321 |
| M1.8 | 1.45 | 1.421 | 1.521 |
| M2 | 1.6 | 1.567 | 1.679 |
| M2.2 | 1.75 | 1.713 | 1.838 |
| M2.5 | 2.05 | 2.013 | 2.138 |
| M3 | 2.5 | 2.459 | 2.599 |
| M3.5 | 2.9 | 2.85 | 3.01 |
| M4 | 3.3 | 3.242 | 3.422 |
| M5 | 4.2 | 4.134 | 4.334 |
| M6 | 5 | 4.917 | 5.153 |
| M7 | 6 | 5.917 | 6.153 |
| M8 | 6.8 | 6.647 | 6.912 |
| M9 | 7.8 | 7.647 | 7.912 |
| M10 | 8.5 | 8.376 | 8.676 |
| M11 | 9.5 | 9.376 | 9.676 |
| M12 | 10.2 | 10.106 | 10.441 |
| M14 | 12 | 11.835 | 12.21 |
| M16 | 14 | 13.835 | 14.21 |
| M18 | 15.5 | 15.294 | 15.744 |
| M20 | 17.5 | 17.294 | 17.744 |
| M22 | 19.5 | 19.294 | 19.744 |
| M24 | 21 | 20.752 | 21.252 |
| M27 | 24 | 23.752 | 24.252 |
| M30 | 26.5 | 26.211 | 26.771 |
| M33 | 29.5 | 29.211 | 29.771 |
| M36 | 32 | 31.67 | 32.27 |
| M39 | 35 | 34.67 | 35.27 |
| M42 | 37.5 | 37.129 | 37.799 |
| M48 | 43 | 42.587 | 43.297 |
| M52 | 47 | 46.587 | 47.297 |
| M56 | 50.5 | 50.046 | 50.796 |
| M60 | 54.5 | – | – |
| M64 | 58 | – | – |
Tap drill sizes for metric fine threads
| Thread | Drillmm | D1 min6H, mm | D1 max6H, mm |
|---|---|---|---|
| M1 × 0.2 | 0.8 | – | – |
| M1.1 × 0.2 | 0.9 | – | – |
| M1.2 × 0.2 | 1 | – | – |
| M1.4 × 0.2 | 1.2 | – | – |
| M1.6 × 0.2 | 1.4 | – | – |
| M1.8 × 0.2 | 1.6 | – | – |
| M2 × 0.25 | 1.75 | – | – |
| M2.2 × 0.25 | 1.95 | – | – |
| M2.5 × 0.35 | 2.15 | 2.121 | 2.221 |
| M3 × 0.35 | 2.65 | 2.621 | 2.721 |
| M3.5 × 0.35 | 3.15 | 3.121 | 3.221 |
| M4 × 0.5 | 3.5 | 3.459 | 3.599 |
| M4.5 × 0.5 | 4 | 3.959 | 4.099 |
| M5 × 0.5 | 4.5 | 4.459 | 4.599 |
| M5.5 × 0.5 | 5 | 4.959 | 5.099 |
| M8 × 1 | 7 | 6.917 | 7.153 |
| M9 × 1 | 8 | 7.917 | 8.153 |
| M9 × 0.75 | 8.2 | 8.188 | 8.378 |
| M10 × 1.25 | 8.8 | 8.647 | 8.912 |
| M10 × 1 | 9 | 8.917 | 9.153 |
| M10 × 0.75 | 9.2 | 9.188 | 9.378 |
| M11 × 1 | 10 | 9.917 | 10.153 |
| M11 × 0.75 | 10.2 | 10.188 | 10.378 |
| M12 × 1.5 | 10.5 | 10.376 | 10.676 |
| M12 × 1.25 | 10.8 | 10.647 | 10.912 |
| M12 × 1 | 11 | 10.917 | 11.153 |
| M14 × 1.5 | 12.5 | 12.376 | 12.676 |
| M14 × 1.25 | 12.8 | 12.647 | 12.912 |
| M14 × 1 | 13 | 12.917 | 13.153 |
| M15 × 1.5 | 13.5 | 13.376 | 13.676 |
| M15 × 1 | 14 | 13.917 | 14.153 |
| M16 × 1.5 | 14.5 | 14.376 | 14.676 |
| M16 × 1 | 15 | 14.917 | 15.153 |
| M17 × 1.5 | 15.5 | 15.376 | 15.676 |
| M17 × 1 | 16 | 15.917 | 16.153 |
| M18 × 2 | 16 | – | – |
| M18 × 1.5 | 16.5 | 16.376 | 16.676 |
| M18 × 1 | 17 | 16.917 | 17.153 |
| M20 × 2 | 18 | 17.835 | 18.21 |
| M20 × 1.5 | 18.5 | 18.376 | 18.676 |
| M20 × 1 | 19 | 18.917 | 19.153 |
| M22 × 2 | 20 | 19.835 | 20.21 |
| M22 × 1.5 | 20.5 | 20.376 | 20.676 |
| M22 × 1 | 21 | 20.917 | 21.153 |
| M24 × 2 | 22 | 21.835 | 22.21 |
| M24 × 1.5 | 22.5 | 22.376 | 22.676 |
| M24 × 1 | 23 | 22.917 | 23.153 |
| M25 × 2 | 23 | 22.835 | 23.21 |
| M25 × 1.5 | 23.5 | 23.376 | 23.676 |
| M25 × 1 | 24 | 23.917 | 24.153 |
| M27 × 2 | 25 | 24.835 | 25.21 |
| M27 × 1.5 | 25.5 | 25.376 | 25.676 |
| M27 × 1 | 26 | 25.917 | 26.153 |
| M28 × 2 | 26 | 25.835 | 26.21 |
| M28 × 1.5 | 26.5 | 26.376 | 26.676 |
| M28 × 1 | 27 | 26.917 | 27.153 |
| M30 × 3 | 27 | 26.752 | 27.252 |
| M30 × 2 | 28 | 27.835 | 28.21 |
| M30 × 1.5 | 28.5 | 28.376 | 28.676 |
| M30 × 1 | 29 | 28.917 | 29.153 |
| M32 × 2 | 30 | 29.835 | 30.21 |
| M32 × 1.5 | 30.5 | 30.376 | 30.676 |
| M33 × 3 | 30 | 29.752 | 30.252 |
| M33 × 2 | 31 | 30.835 | 31.21 |
| M33 × 1.5 | 31.5 | 31.376 | 31.676 |
| M35 × 2 | 33 | – | – |
| M35 × 1.5 | 33.5 | 33.376 | 33.676 |
| M36 × 3 | 33 | 32.752 | 33.252 |
| M36 × 2 | 34 | – | – |
| M36 × 1.5 | 34.5 | 34.376 | 34.676 |
| M39 × 3 | 36 | – | 36.252 |
| M39 × 2 | 37 | – | – |
| M39 × 1.5 | 37.5 | – | – |
| M40 × 3 | 37 | – | – |
| M40 × 2 | 38 | – | – |
| M40 × 1.5 | 38.5 | – | – |
| M42 × 4 | 38 | – | – |
| M42 × 3 | 39 | 38.752 | 39.252 |
| M42 × 2 | 40 | – | – |
| M42 × 1.5 | 40.5 | – | – |
| M45 × 4 | 41 | – | – |
| M45 × 3 | 42 | 41.752 | 42.252 |
| M45 × 2 | 43 | – | – |
| M45 × 1.5 | 43.5 | – | – |
| M48 × 4 | 44 | – | – |
| M48 × 3 | 45 | 44.752 | 45.252 |
| M48 × 2 | 46 | – | – |
| M48 × 1.5 | 46.5 | – | – |
| M50 × 3 | 47 | – | – |
| M50 × 2 | 48 | – | – |
| M50 × 1.5 | 48.5 | – | – |
| M52 × 4 | 48 | 47.67 | 48.27 |
| M52 × 3 | 49 | – | – |
| M52 × 2 | 50 | – | – |
| M52 × 1.5 | 50.5 | – | – |
| M55 × 4 | 51 | – | – |
| M55 × 3 | 52 | – | – |
| M55 × 2 | 53 | – | – |
| M55 × 1.5 | 53.5 | – | – |
| M56 × 4 | 52 | – | – |
| M56 × 3 | 53 | – | – |
| M56 × 2 | 54 | – | – |
| M56 × 1.5 | 54.5 | – | – |
| M58 × 4 | 54 | – | – |
| M58 × 3 | 55 | – | – |
| M58 × 2 | 56 | – | – |
| M58 × 1.5 | 56.5 | – | – |
| M60 × 4 | 56 | – | – |
| M60 × 3 | 57 | – | – |
| M60 × 2 | 58 | – | – |
| M60 × 1.5 | 58.5 | – | – |
| M62 × 4 | 58 | – | – |
| M62 × 3 | 59 | – | – |
| M62 × 2 | 60 | – | – |
| M62 × 1.5 | 60.5 | – | – |
| M64 × 4 | 60 | – | – |
| M64 × 3 | 61 | – | – |
| M64 × 2 | 62 | – | – |
| M64 × 1.5 | 62.5 | – | – |
Sources the values were checked against (7)
- Hartner, Kernlochdurchmesser für das Gewindeschneiden (DIN 336 y limites de la tuerca 6H)
- Engineers Edge, rosca interior metrica 6H (ANSI/ASME B1.13M-1995), columna Tap Drill Basic y D1 min./max.
- AmesWeb, Metric Tap Drill Chart (D1 min. y max. 6H y broca)
- Get It Made, Metric Thread Chart (columna Tap Drill)
- Engineering ToolBox, ISO metric threads (tap drill, gruesa y fina)
- Made Good Designs, Tap Drill Chart (d - P, 77 % de rosca)
- draftsperson.net, ISO metric die and tap sizes (Misumi la copia)
M6, M8, M10 and M12 tap drill sizes
The most used coarse threads take these drills: M3 2.5 mm, M4 3.3 mm, M5 4.2 mm, M6 5.0 mm, M8 6.8 mm, M10 8.5 mm, M12 10.2 mm, M14 12.0 mm, M16 14.0 mm, M20 17.5 mm and M24 21.0 mm. For fine threads: M8 × 1 7.0 mm, M10 × 1.25 8.8 mm, M10 × 1 9.0 mm and M12 × 1.5 10.5 mm.
How the tap drill size is chosen
The drill is close to the nominal diameter minus the pitch, rounded to a drill size that leaves the hole within the nut minor diameter limits of class 6H shown in the table. Some charts give a drill 0.05 mm smaller for some sizes (6.75 mm for M8); both fall inside the limits. The values here follow the most common choice, checked against at least two independent sources. For forming taps, which displace the material instead of cutting it, the drill is larger: use the tap maker's value.
The full thread dimensions are in the metric thread chart.
Tap drill sizes: common questions
- What size drill for an M8 tap?
- 6.8 mm for the coarse thread M8 × 1.25, and 7.0 mm for the fine thread M8 × 1.
- What size drill for an M6 tap?
- 5.0 mm for the coarse thread M6 × 1.
- What size drill for an M10 tap?
- 8.5 mm for the coarse thread M10 × 1.5, 8.8 mm for M10 × 1.25 and 9.0 mm for M10 × 1.
- What size drill for an M12 tap?
- 10.2 mm for the coarse thread M12 × 1.75, and 10.5 mm for the fine thread M12 × 1.5.