Manufacturing · Machining
Drill Point Depth Calculator
Size the conical tip allowance from diameter and point angle — watch the cross-section update as you dial in 118°, 135°, or a custom grind.
Result
Point depth
h = D / (2 tan(θ/2))
Enter diameter and point angle — the cross-section diagram tracks your geometry live.
Reference for conical drill-tip geometry and CNC depth planning.
Drill point depth is the distance from the tip of a twist drill to where the cutting edges reach full diameter. Machinists add this allowance when programming blind holes, setting drill stops, or avoiding breakthrough on thin stock.
- Flat surfaceh = D / (2 tan(θ/2))
- Angled surfaceh = D / (2 tan(|θ/2 − β|))
- Full hole depthZ_total = Z_shoulder + h
D = drill diameter, θ = point angle (included), β = surface angle from horizontal, h = point depth.
118°
Standard point
Most common for general-purpose HSS drills in steel, cast iron, and plastics.
135°
Split / flat point
Self-centering on hard materials; reduced walking on stainless and alloy steels.
90°
Screw-machine point
Sharper tip for brass, aluminum, and other soft non-ferrous alloys.
- CNC programming — offset Z depth so the full diameter lands at the design shoulder
- Blind holes — avoid under-drilling when the drawing dimension is to full diameter
- Drill press stops — set mechanical depth limits including the conical section
- Thin sheet — predict breakthrough before the tip exits the far side
- Spot drills & center drills — compare tip geometry before secondary operations
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