Drill Point Depth Calculator
How much the 118° or 135° drill tip adds to a blind hole — tip height and the total depth to program for full diameter.
A 118° drill's cone adds almost exactly 0.3×D to the hole — 3 mm of dead depth on a 10 mm drill — and a 135° split point adds about 0.21×D. CAM systems differ on whether 'drill depth' means the tip or the shoulder, and a tapped blind hole needs full diameter for every thread you count, plus chip room below the tap's chamfer lead. Check which convention your post uses before the first part, not after.
Formula
Note: Thinned and webbed points alter the effective tip height slightly; for depth-critical blind holes verify the first part with a depth micrometer.
How much the 118° or 135° drill tip adds to a blind hole — tip height and the total depth to program for full diameter. A free machinist & fabrication essentials tool — no sign-up, no upload, instant results in your browser.
About Drill Point Depth Calculator
Drill Point Depth Calculator computes the governing relationship tip = (D/2) / tan(θ/2) ; program depth = required full-Ø depth + tip live as you type. A 118° drill's cone adds almost exactly 0.3×D to the hole — 3 mm of dead depth on a 10 mm drill — and a 135° split point adds about 0.21×D. CAM systems differ on whether 'drill depth' means the tip or the shoulder, and a tapped blind hole needs full diameter for every thread you count, plus chip room below the tap's chamfer lead. Check which convention your post uses before the first part, not after. Defaults are pre-filled with realistic values for this exact scenario, and the worked example substitutes your numbers step by step so the math is never a black box.
How to use Drill Point Depth Calculator
- 1Enter your values — Drill diameter, Point angle, Required full-Ø depth (sensible defaults are pre-filled).
- 2Read the live results: Drill tip height, Program depth (to tip).
- 3Check the "with your numbers" line to see tip = (D/2) / tan(θ/2) ; program depth = required full-Ø depth + tip substituted step by step.
- 4Adjust inputs until the scenario matches yours, then copy or share the result.
Why use Drill Point Depth Calculator?
- ✓Instant, free and private — every calculation runs client-side in your browser; nothing is uploaded
- ✓Built on the stated formula tip = (D/2) / tan(θ/2) ; program depth = required full-Ø depth + tip with authoritative sources cited on the page (Machinery's Handbook, 31st ed.; ISO 235 / DIN 338 — Twist drills, point geometry)
- ✓A 118° drill's cone adds almost exactly 0.3×D to the hole — 3 mm of dead depth on a 10 mm drill — and a 135° split point adds about 0.21×D.
- ✓SI ⇄ Imperial toggle converts your inputs in place, so you can work in the units your drawings use
Frequently asked questions
What formula does the drill point depth calculator use?+
It evaluates tip = (D/2) / tan(θ/2) ; program depth = required full-Ø depth + tip, exactly as published. Sources: Machinery's Handbook, 31st ed.; ISO 235 / DIN 338 — Twist drills, point geometry. The substituted worked example on the page lets you verify every step against the textbook.
How should I read the result — and how far can I trust it?+
A 118° drill's cone adds almost exactly 0.3×D to the hole — 3 mm of dead depth on a 10 mm drill — and a 135° split point adds about 0.21×D. Thinned and webbed points alter the effective tip height slightly; for depth-critical blind holes verify the first part with a depth micrometer.
When is this calculator the right tool for the job?+
How much the 118° or 135° drill tip adds to a blind hole. CAM systems differ on whether 'drill depth' means the tip or the shoulder, and a tapped blind hole needs full diameter for every thread you count, plus chip room below the tap's chamfer lead. For neighbouring scenarios, the related tools below cover the same engine with different presets.
Does it support both metric and imperial units?+
Yes — the SI ⇄ Imperial toggle converts the values already in the fields, preserving the physical quantity, so you can flip mid-calculation without re-entering anything.
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