Tap Drill Size Chart

M16 x 2 Tap Drill Size

Tap drill

14 mm 0.5512 in

Use a 14 mm drill (0.5512 in) for 77.0% thread.

Fine thread M16 x 1.5? Use 14.5 mm. (0.5709 in, 77.0% thread)

The drill size for a M16 x 2 tap is 14 mm (0.5512 in). If you are wondering what size drill bit a M16 x 2 tap needs, that is the one: it leaves 77.0% of thread, which is the figure standard tap and drill charts are built around. Below are the other holes you might want for this size - a larger drill for tough material, the form-tap hole, and the clearance holes for the bolt that goes in.

Every drill for M16 x 2

Tap drills and clearance drills for M16 x 2 (Metric coarse, 2 mm pitch). Percent of thread is the figure stored for each drill, which reproduces from the major diameter and pitch of M16 x 2.
Use Drill Decimal in mm % thread
Standard tap drill Cut tap, general use (D - P) 14 mm 0.5512 14.00 77.0%
Inch substitute Closest inch drill if you have no metric set 35/64″ 0.5469 13.89 81.2%
Hard material Stainless, tool steel, anything that fights the tap 14.4 mm 0.5669 14.40 61.6%
Form (roll) tap Theoretical 15.12 mm - starting point, check your tap maker's chart 15.1 mm 0.5945 15.10 —

Clearance holes for a M16 x 2 bolt

A clearance hole is not tapped. It is the hole in the part the bolt passes through, so it is always larger than the thread.

Clearance holes for M16 x 2 per ISO 273. Clearance depends on the bolt diameter alone, so every M16 thread shares these figures.
Fit Hole mm Hole in
Fine 17.00 0.6693
Medium 17.50 0.689
Coarse 18.50 0.7283

M16 x 2 dimensions

Nominal dimensions for M16 x 2. The basic internal minor diameter is the hole a 100% thread would start from, which is why no tap drill is ever that small.
Dimension Inch mm
Major diameter 0.6299 16.00
Basic internal minor diameter 0.5447 13.84
Pitch 0.0787 2.00
Thread designation M16 x 2

What the hole looks like

Cross-section of a M16 x 2 tapped hole, drawn to scale The drilled hole is 14 mm, 0.5512 inches or 14.00 millimetres across. The tap cuts outward from that wall to the major diameter of 0.6299 inches. A 100 percent thread would reach in to the basic minor diameter of 0.5447 inches, shown as a dashed line; the difference is why this drill gives 77.0% of thread. major 16 mm drill 14 mm · 14 mm dashed = 100% thread at 13.84 mm
M16 x 2 in section, to scale. The accent line is the thread the tap cuts from a 14 mm hole; the dashed line is where the crest would sit at 100% thread. The gap between them is the 23.0% of thread this drill leaves behind.

Work out a different hole for M16 x 2

Pre-filled with M16 x 2. Change the material, the tap type, or which drills you actually own, and it picks the closest real drill and tells you the percent of thread you end up with. The tables above are the published figures and do not depend on this.

The general-purpose target

Tap type
Drills you have

Best drill you have, cut tap, 70% target

14.2 mm0.5591 in69.3% thread

Theoretical hole 14.18 mm

One size down, deeper thread14.1 mm 0.5551 in · 73.1%

One size up, easier tapping9/16″ 0.5625 in · 65.9%

For comparison, the published chart drill for M16 x 2 is 14 mm at 77.0% thread.

Notes on M16 x 2

Coarse pitch
M16 x 2 is the coarse pitch at 16 mm. It is the usual choice for general work, and it tolerates a slightly off-size hole better than the finer pitches do. Finer options at the same diameter: M16 x 1.5, M16 x 1.
What the standard drill gives you
14 mm leaves 77.0% of thread (D - P). That is in the normal 65-80% band most shop charts aim for.
Stainless, tool steel and other tough material
14.4 mm opens the hole to 61.6% engagement. Less material for the tap to cut means less torque and less heat, at the cost of some thread depth.
Using a form (roll) tap
A form tap displaces metal instead of cutting it, so it needs a larger hole: 15.1 mm, against a theoretical 15.12 mm. Treat that as a starting point and check your tap maker's chart.
Closest inch size
5/8-11 is the nearest inch thread by diameter (15.88 mm against 16 mm). It is a planning reference only. The two are not interchangeable: the pitches differ, and a bolt from one will not run into a hole tapped for the other.

Related sizes

Same diameter, different pitch

Next size up and down

Closest inch size

5/8-11 17/32″ · 0.5312 in · 13.49 mm · 79.4% 15.88 mm major against 16 mm

Not interchangeable. 5/8-11 is the nearest size by diameter, nothing more. The pitches differ, so a 5/8-11 fastener will not run into a M16 x 2 hole and forcing one will strip both.

Guides for tapping M16 x 2

Longer reads on the decisions behind the numbers above.

All guides →

M16 x 2 tap drill: common questions

What size drill bit do I need for a M16 x 2 tap?
A 14 mm drill, 0.5512 in. That leaves 77.0% of thread, which is the standard chart figure for M16 x 2.
What is the drill size for a M16 x 2 tap in inches?
The 14 mm tap drill measures 0.5512 in. If you only have inch drills, 35/64 in (0.5469 in) is the closest, giving 81.2% thread.
What drill should I use for M16 x 2 in stainless steel?
Use 14.4 mm instead of 14 mm. It leaves 61.6% of thread rather than 77.0%, so there is less material for the tap to cut and less chance of snapping it.
Is M16 x 2 the same as M16 x 1.5?
No. Both are 16 mm threads, but the pitch differs, so the drills differ: 14 mm for M16 x 2 and 14.5 mm for M16 x 1.5. The taps and the fasteners are not interchangeable.
What is the clearance hole for an M16 x 2 bolt?
For a medium fit, 17.5 mm per ISO 273. A clearance hole is not tapped; the bolt passes straight through it.
A 4 × 6 in card with the drills for this size.