⏱️ Drilling Cycle Time

Written and maintained by the PhDino author · Last reviewed 21 September 2026 · Checked against 1 independent reference calculation · how PhDino checks its numbers

Estimating how long a drilling operation takes from spindle speed, feed, and hole count.

Machining cycle time estimation starts from a simple idea: time equals distance divided by speed, applied to the tool's travel through the material. For drilling, that distance is the hole depth plus a small clearance allowance for the drill to approach the part and clear it afterward, and the speed is the feed rate the drill advances at.

Feed rate itself comes from spindle speed and feed per revolution — the same relationship used in general CNC speeds and feeds, just applied specifically to the axial (depth-wise) travel of a drilling operation rather than the lateral travel of a milling cut.

Key formula

Feed rate (IPM) = spindle speed (RPM) × feed per revolution
Time per hole = (hole depth + clearance) ÷ feed rate
Total time = time per hole × number of holes

Notes & limitations

• This is pure cutting time — it doesn't include tool-change time, rapid traverse moves between hole locations, peck-drilling retractions for chip clearing on deep holes, or spindle start/stop time, all of which add to the real total job time on an actual machine.
• Deep holes (rule of thumb: more than about 3–5 times the drill diameter) commonly need peck drilling — periodic full retractions to clear chips — which this simple continuous-feed model doesn't account for, and which meaningfully increases real cycle time over this estimate.