1-1/4 in Drill Size

fractional drill

1-1/4″ 1.250 in 31.75 mm

A 1-1/4 in drill measures 1.250 in. It taps 2 threads in this chart.

What a 1-1/4 in 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.

Threads a 1-1/4 in drill taps, with the percent of thread each one gets and the published chart drill for comparison.
Thread	% thread	Chart drill	Chart %
M36 x 4	81.8%	32 mm	77.0%
1-3/8-6	57.7%	1-7/32″	72.1%

Other jobs for a 1-1/4 in

Hard-material tap drill: The size to use in stainless or tool steel for 1-3/8-6, where it leaves a shallower thread than the standard drill and cuts tapping torque.

Drills either side

31.5 mm 1.2402 in · 31.5 mm Next size down
32 mm 1.2598 in · 32 mm Next size up

All drill sizes → · Open this drill in the calculator →

1-1/4 in drill: common questions

What size is a 1-1/4 in drill?

1.250 inches, which is 31.75 mm. It is a fractional drill.

What can I tap with a 1-1/4 in drill?

2 threads: M36 x 4 at 81.8%, 1-3/8-6 at 57.7%.

What drill is next to a 1-1/4 in?

Down: 31.5 mm at 1.2402 in. Up: 32 mm at 1.2598 in.