Drill Point Length Calculator

Inputs

Drill diameter (D)

Drill body diameter. The cone point length scales directly with diameter.

Point angle (A)

Included point angle at the drill tip. Common twist drills are 118 degrees or 135 degrees.

Full-diameter depth (H)

Depth that must be at full drill diameter. The point length is added to get total drilling depth.

Default result

Point length(L_p)

3.004mm

Pass

Add this to the required full-diameter depth for a blind hole.

Axial length of the conical drill point.

Also computed

Total drill depth(H + L_p)23mm

Programmed depth to get the entered full-diameter depth.

Half angle(A/2)59°

Method notes 3 notes

Drill point length is Lp = (D/2)/tan(A/2), where A is the included point angle.
For blind holes, total drilling depth = required full-diameter depth + point length.
This assumes a sharp conical drill point. Split points, web thinning, tip flats, regrinds, center drills and drill wander can change the practical allowance.