#43 Drill Size
number drill
#43 0.089 in 2.26 mm
A #43 drill is the standard tap drill for #4-40.
What a #43 drill taps
Every thread this drill cuts between 50% and 85% of thread, deepest first. Outside that band it is the wrong drill for the job, so nothing below that line is listed.
Other jobs for a #43
- Form-tap hole
- The published roll-tap hole for #3-48, #3-56. A form tap displaces metal instead of cutting it, so it needs this larger hole.
- Clearance hole
- The through hole a bolt passes in, not a tapped hole: normal fit for #1-64, normal fit for #1-72. See the clearance hole chart.
Drills either side
#43 drill: common questions
What size is a #43 drill?
0.089 inches, which is 2.26 mm. It is a number drill.
What can I tap with a #43 drill?
2 threads: #4-48 at 85.0%, #4-40 at 70.8%.
Is a #43 drill the standard tap drill for anything?
Yes, for #4-40 (70.8% thread). That is the size published tap and drill charts give.
Is a #43 drill used for clearance holes?
Yes: normal fit for #1-64, normal fit for #1-72. A clearance hole is not tapped; the bolt passes through it.
What drill is next to a #43?
Down: 2.2 mm at 0.0866 in. Up: 2.3 mm at 0.0906 in.