Drill Feed Calculator
Turn spindle RPM and feed per revolution into the table feed (IPM) to program — drilling feed is set per revolution, not per tooth.
Typical feed per revolution by drill diameter
| Drill diameter | Feed per rev, HSS (in) |
|---|---|
| Under 1/8" | 0.001–0.003 |
| 1/8" – 1/4" | 0.002–0.004 |
| 1/4" – 1/2" | 0.004–0.007 |
| 1/2" – 3/4" | 0.007–0.010 |
| 3/4" – 1" | 0.010–0.015 |
| Over 1" | 0.015–0.025 |
General ranges for drilling mild steel with an HSS twist drill in a rigid setup — scale down for harder materials or deep, unsupported holes, and up for softer, free-machining materials.
Why drilling feed works differently from milling feed
A twist drill is specified by feed per revolution (IPR), not feed per tooth, even though it usually has two cutting lips — that's because the two lips of a standard twist drill are ground to cut together as a matched pair, so the practical control variable is how far the whole drill advances per spindle revolution, not a per-flute chip load like an end mill. Feed rate (IPM) = RPM × feed per revolution converts that into the number you actually program.
Bigger holes can take a bigger bite, up to a point
Larger drills have a longer cutting lip and more mass supporting the cut, which is why the recommended feed per revolution scales up with diameter — but it doesn't scale linearly forever. Very large drills are limited more by torque and the machine's ability to clear chips from a deep flute than by the lip length alone, so treat the top of any diameter range as a starting point to dial back from, not a guarantee.
The first sign you've pushed feed too far
A drill that feeds too aggressively for its diameter and material typically shows it through a burnt or discolored chip, a hole that walks off-center, or the drill point chipping or snapping outright on entry — all signs the feed is ahead of what the point geometry and flute can actually clear. Back off feed rate before RPM if you see any of these, since drilling problems are far more often a feed issue than a speed issue.