196.3495 ft/min is the example result. Read it using the units and relationship stated below.
CNC Drill Speed uses spindle speed (rpm), drill diameter (in).
Keeping feed calculations attached to the cutting conditions
For cnc drill speed, the relationship is Result = Math.PI × [Drill diameter (in)] × [Spindle speed (RPM)] ÷ 12. The amount depends on the supplied spindle speed (rpm), drill diameter (in), rather than a live market price or a value imported from another record. A machining relationship connects diameter, speed, feed and engagement. It does not choose a safe starting point without the cutter, material and setup. Manufacturer cutting data should provide the process assumptions used in the form.
What the model includes
Result = Math.PI × [Drill diameter (in)] × [Spindle speed (RPM)] ÷ 12 Keep millimetres and metres distinct, and record whether feed is per tooth, per revolution or per minute. A correct conversion can still be unsuitable when tool reach, workholding, machine limits or chip evacuation changes. Use the result as a conversion or comparison, then validate the process against the tool guidance and machine capability. This page does not replace a tested setup sheet or account for every cutting condition.
Example with the supplied inputs
Spindle speed (RPM): 3000; Drill diameter (in): 0.25. Result: 196.3495 ft/min. The values are illustrative.
Compare one changed input
Drill diameter (in) changes from 0.25 to 0.275. The result becomes 215.9845 ft/min. All other inputs remain fixed.
Calculation rule
Result = Math.PI × [Drill diameter (in)] × [Spindle speed (RPM)] ÷ 12
Inputs and output
| Input | Example value | Entry convention |
|---|---|---|
| Spindle speed (RPM) | 3000 | Measure spindle speed (rpm) in the displayed unit. Convert the source measurement before entry if it uses another system; a changed label does not perform a unit conversion. |
| Drill diameter (in) | 0.25 | Measure drill diameter (in) in the displayed unit. Convert the source measurement before entry if it uses another system; a changed label does not perform a unit conversion. |
Output: 196.3495 ft/min is the example result. Read it using the units and relationship stated below. Unit: ft/min.
How to use the page
Collect the inputs
Gather Spindle speed (RPM), Drill diameter (in). Use one period and the units shown in the form.
Run the calculation
Enter the values and select the action. The calculation rule above explains how the inputs produce the result.
Compare a scenario
Change Drill diameter (in) on its own, keeping the other inputs fixed. Read both results before changing another assumption.
Worked example
With the example inputs listed above, the result is 196.3495 ft/min.
Change Drill diameter (in) from 0.25 to 0.275 while keeping every other value fixed. The result becomes 215.9845 ft/min. This comparison isolates that input; it does not forecast how other variables will respond.
Check the stated formula, units and limits before using the result in a decision.
Keep the displayed formula, input units and model scope with the result. Corrections or questions can be sent through the request section on this page.
Content updated: October 11, 2026