# M6 tap drill size

URL: https://www.clove3d.com/tools/tap-drill/m6/

Tap drill for M6 × 1: 5.0 mm (0.1969 in / 5.00 mm), about 77% thread.

## Thread specs

- Series: ISO metric coarse
- Major diameter: 6.00 mm
- Pitch: 1 mm
- Basic minor diameter: 4.92 mm

## Every drill that works (50-85% thread)

| Drill | % thread | in | mm | Good for |
|---|---|---|---|---|
| #4 | 53% | 0.2090 | 5.31 | deep holes only |
| 5.3 mm | 54% | 0.2087 | 5.30 | deep holes only |
| #5 | 60% | 0.2055 | 5.22 | hard or tough metals |
| 5.2 mm | 62% | 0.2047 | 5.20 | hard or tough metals |
| #6 | 63% | 0.2040 | 5.18 | hard or tough metals |
| 13/64" | 65% | 0.2031 | 5.16 | hard or tough metals |
| #7 | 69% | 0.2010 | 5.11 | hard or tough metals |
| 5.1 mm | 69% | 0.2008 | 5.10 | hard or tough metals |
| #8 | 73% | 0.1990 | 5.05 | general use |
| 5.0 mm (standard) | 77% | 0.1969 | 5.00 | general use |
| #9 | 79% | 0.1960 | 4.98 | general use |
| #10 | 84% | 0.1935 | 4.91 | more torque, more broken taps |
| 4.9 mm | 85% | 0.1929 | 4.90 | more torque, more broken taps |

## Clearance hole

- Close (fine): 6.4 mm (0.2520 in / 6.40 mm)
- Normal (medium): 6.6 mm (0.2598 in / 6.60 mm)
- Loose (coarse): 7.0 mm (0.2756 in / 7.00 mm)

## Counterbore (socket head cap screw)

- NBK: diameter 11.00 mm, depth 6.50 mm
- AMES: diameter 11.25 mm, depth 6.00 mm

Countersink (flat head socket screw): 90 degrees to 13.44 mm across for a flush head.

## Heat-set insert hole (3D prints)

- CNC Kitchen: 8.00 mm
- Accu: 8.00 mm
- Generic (Albany County): 7.60 mm

## Thread repair (Helicoil / STI drill)

- MISUMI: 6.2 mm (0.2441 in / 6.20 mm)

## FAQ

Q: What size drill do I use for an M6 tap?
A: Use a 5.0 mm (5.00 mm / 0.1969 in) drill. It leaves about 77% thread, the standard for general-purpose tapping.

Q: What inch drill can I use for an M6 tap?
A: #9 (4.98 mm / 0.1960 in) is the closest, giving about 79% thread. Anything from about 65% to 80% thread taps well in most materials.

Q: What size clearance hole for an M6 screw?
A: 6.4 mm (6.40 mm) for a close fit, 6.6 mm (6.60 mm) for a normal fit.

Q: What hole size for an M6 heat-set insert?
A: Between 7.6 mm and 8.0 mm depending on the brand: CNC Kitchen 8.0 mm, Accu 8.0 mm, Generic (Albany County) 7.6 mm. Use your insert's own number.

Q: What is the inch equivalent of M6?
A: 1/4-20 is the closest size (6.35 mm vs 6.00 mm major diameter). The pitches differ, so the screws and tapped holes are not interchangeable.

## Sources

- Engineers Edge: metric ISO tap drill chart: https://www.engineersedge.com/manufacturing/metric-iso-tap-drill-chart.htm
- Penn MEDesign: tap drill chart: https://medesign.seas.upenn.edu/index.php/Guides.TapDrillChart
- Albany County Fasteners: clearance hole chart (PDF): https://www.albanycountyfasteners.com/media/6b/b8/g0/1764944339/clearance-hole-chart.pdf
- AMES: metric clearance hole chart (ASME B18.2.8): https://amesweb.info/Screws/Metric-Clearance-Hole-Chart.aspx
- NBK: dimensions of holes for hexagon socket head cap screws: https://alb02.internal.nbk1560.com/en/resources/other/article/technical-22-dimensions-of-holes-for-hexagon-socket-cap-screws
- AMES: counterbore hole dimensions, metric (Machinery's Handbook): https://amesweb.info/Screws/Metric-Counterbore-Hole-Dimensions-Chart.aspx
- Global Fastener: ISO 10642 hexagon socket countersunk head screws: https://www.globalfastener.com/standards/detailn_182.html
- Eugene Fastener: flat head socket screw countersink guide: https://www.eugenefast.com/Home/Page/resources/flat-head-socket-screw-countersink-guide
- SC Fastening: flat head socket cap screw spec, ASME B18.3 (PDF): https://scfastening.com/wp-content/uploads/2017/06/flatsocketspec.pdf
- CNC Kitchen threaded inserts (3DJake listing, hole diameter D3): https://www.3djake.ch/en-CH/cnc-kitchen/threaded-inserts-m5-short
- Accu: threaded insert hole size charts for 3D printing: https://accu-components.com/us/p/488-threaded-insert-hole-size-charts-for-3d-printing-pla-petg-resin
- Albany County Fasteners: heat-set insert specs (PDF): https://www.albanycountyfasteners.com/media/64/3d/5a/1764619189/heat-set-insert-specs.pdf
- MISUMI: Helicoil tap and drill size chart: https://blog.misumiusa.com/helicoil-tap-and-drill-size-chart/