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Calculate drill tip height from diameter and point angle. Add it to full-diameter hole depth to find total drilling depth, with a worked example.
Drill point
1What point angle does your drill have?
2Enter the measurements
Total Z = usable depth (at full Ø) + point height. In through holes, add the point as break-out so it goes right through.
3Result
Click a dimension to copy it
In a blind hole, the drill tip reaches deeper than the full-diameter cylindrical section. Enter diameter, included point angle and the required useful depth. The output separates cone height from total depth measured to the tip.
Known measurements
Ø8 mm drill · 118° point · 20 mm useful depth
Result
Point height ≈ 2.403 mm · total depth ≈ 22.403 mm
With the same diameter and a 135° point, tip height becomes approximately 1.657 mm.
A useful depth of 20 mm requires 20 mm of full-diameter cylindrical hole. A 2.4 mm point then needs to reach approximately 22.4 mm. A drawing dimension already measured to the tip needs a different interpretation: do not add the cone again.
An ideal conical point uses h = (Ø/2)/tan(θ/2). At 118°, its height is approximately 0.3004 × Ø; at 135°, approximately 0.2071 × Ø. The quick 0.3 × diameter rule therefore does not apply equally to every point angle.
Actual drills may have split points, facets or another tip form. The calculator adds no breakthrough clearance and does not check remaining wall thickness. Confirm the useful dimension, point form and hole-bottom location before setting cycle Z.
The cylindrical hole length at the nominal drill diameter, excluding the conical bottom.
It approximates an ideal 118° point. Use the drill's actual point angle for other grinds.
No. It calculates geometric point height and adds useful depth. Choose exit clearance for the actual part, fixture and tool.
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