M16 tap drill size
Drill a 14.0 mm hole (0.5512") for an M16 × 2 tap. That leaves about 77% thread, the standard for general-purpose tapping.
M16 tap drill: 14.0 mm (0.5512 in / 14.00 mm), 77% threadM16 thread specs
| Series | ISO metric coarse |
|---|---|
| Major diameter | 16.00 mm (0.6299") |
| Pitch | 2 mm (12.7 TPI) |
| Basic minor diameter | 13.83 mm (0.5447") |
| Common internal class | 6H |
Every drill that works for M16
Drills from all four sets that give 50–85% thread, largest first. Lower percentages tap easier; see how much thread you need.
| Drill | Thread | in | mm | Set | Good for |
|---|---|---|---|---|---|
| 37/64" | 51% | 0.5781 | 14.68 | Fractional | deep holes only |
| 14.5 mm | 58% | 0.5709 | 14.50 | Metric | deep holes only |
| 9/16" | 66% | 0.5625 | 14.29 | Fractional | hard or tough metals |
| 14.0 mmstandard | 77% | 0.5512 | 14.00 | Metric | general use |
| 35/64" | 81% | 0.5469 | 13.89 | Fractional | more torque, more broken taps |
M16 clearance hole
The hole a M16 screw passes through. ISO 273 fine, medium and coarse series.
| Fit | mm | in |
|---|---|---|
| Close (fine) | 17.0 mm | 0.6693 |
| Normal (medium) | 17.5 mm | 0.6890 |
| Loose (coarse) | 18.5 mm | 0.7283 |
M16 counterbore and countersink
For a socket head cap screw to sit flush, and for a flat head socket screw.
| Socket head counterbore | Diameter | Depth |
|---|---|---|
| NBK | 26.00 mm | 17.50 mm |
| AMES | 25.50 mm | 16.00 mm |
Flat head socket screw: countersink at 90° (metric screws, ISO 10642) to 33.60 mm (1.3228") across for a flush head. Inch flat heads use 82°, so don't mix countersinks.
M16 holes in a 3D print
Printed holes usually come out undersize. Model the hole at the drill size plus what your printer loses, then tap or drill to size. Why printed holes shrink.
Print a test hole, measure it with calipers, enter the difference. 0 models the nominal size.
M16 thread repair (Helicoil)
Stripped M16 thread? Drill out with the STI drill, tap with a M16 × 2 STI tap, and fit a wire thread insert. The drill in your repair kit’s instructions wins over any chart.
| Chart | STI drill | in | mm |
|---|---|---|---|
| MISUMI | 16.5 mm | 0.6496 | 16.50 |
Related sizes
Frequently asked questions
What size drill do I use for an M16 tap?
What inch drill can I use for an M16 tap?
What size clearance hole for an M16 screw?
What is the inch equivalent of M16?
Sources
- Engineers Edge: metric ISO tap drill chart checked 2026-10-19
- University of Florida MAE design lab: tap drill chart (PDF) checked 2026-10-19
- Albany County Fasteners: clearance hole chart (PDF) checked 2026-10-19
- AMES: metric clearance hole chart (ASME B18.2.8) checked 2026-10-19
- NBK: dimensions of holes for hexagon socket head cap screws checked 2026-10-19
- AMES: counterbore hole dimensions, metric (Machinery's Handbook) checked 2026-10-19
- Global Fastener: ISO 10642 hexagon socket countersunk head screws checked 2026-10-19
- Eugene Fastener: flat head socket screw countersink guide checked 2026-10-19
- SC Fastening: flat head socket cap screw spec, ASME B18.3 (PDF) checked 2026-10-19
- MISUMI: Helicoil tap and drill size chart checked 2026-10-19
Spotted a wrong number? Email contact@clove3d.com and it gets fixed.
% thread = (major − drill) ÷ (1.299 × pitch) × 100. The standard drill comes from published charts and is checked against this formula on every build.