Calculators
Drill Point Depth Calculator
Find the extra tip length a twist drill's conical point adds, and the total depth to drill so the hole reaches full diameter at your target depth — for 118°, 135°, or any point angle.
Last verified: 2026-07-09
A twist drill cuts a cone at the bottom of the hole, so the tip reaches deeper than the full-diameter portion. Enter the drill diameter, point angle, and the depth you need at full diameter to get the point length and the total depth to program.
Units
Point length
0.1502in
Total drilled depth
1.1502in
Point length = (Ø ÷ 2) ÷ tan(point angle ÷ 2). A standard twist drill needs to advance this much past your target depth for the hole to reach full diameter there.
Frequently asked
- What point angle should I assume?
- 118° is the general-purpose standard; 135° (often a split point) is common for harder materials and self-centering. Use the exact angle of your drill for critical depths.
- Why does this matter for blind holes and tapping?
- The usable full-diameter depth is shallower than where the tip stops. For blind tapped holes especially, account for the point (and the incomplete first threads) so you get enough usable thread.
Sources
- Drill point geometry: point length = (Ø ÷ 2) ÷ tan(point angle ÷ 2)