CNC Drilling Speeds and Feeds Calculator
Enter your drill diameter, cutting speed or RPM, and feed per revolution or feed rate. The calculator converts the values for a standard rotating drilling operation using the units you select.
Your drilling speeds and feeds
Based on drill, cutting data and units entered. These are calculated values, not cutting-data recommendations or a safety approval.
Calculation summary
| Quantity | Value | Status |
|---|---|---|
| Drill diameter | 10.00 mm | Entered |
| Cutting speed | 100.0 m/min | Entered |
| Spindle speed | 3,183 RPM | Calculated |
| Feed per revolution | 0.150 mm/rev | Entered |
| Feed rate | 477.5 mm/min | Calculated |
| Circumference | 31.42 mm | Calculated |
Feed-only drilling time
| Item | Value |
|---|
Enter a feed rate above zero to calculate drilling time.
Feed-only travel time. Excludes rapid approach, retracts, peck cycles, dwell, tool changes, machine acceleration, coolant/chip clearing and all other non-cutting time.
Machine limits
| Limit | Entered | Calculated | Status |
|---|
This only compares figures — it does not clamp or recalculate any value, and staying below a limit is not a safety approval.
Formula used
RPM = (vc × 1,000) ÷ (π × D)
RPM = (100.0 m/min × 1,000) ÷ (π × 10.00 mm) = 3,183 RPM
Feed rate = feed per revolution × RPM
Feed rate = 0.150 mm/rev × 3,183 RPM = 477.5 mm/min
Assumes a single standard rotating drill at a fixed diameter, RPM and feed. Uses the metric and imperial constants above with no rounding until display. Does not model drill geometry beyond the point angle, chip evacuation, peck or retract strategy, tool wear or material variability.
How to use this calculator
- Choose Metric or Imperial units. The operation is fixed: standard rotating drilling.
- Choose what to calculate: RPM and feed rate (from a cutting speed and feed per revolution you already have), or cutting speed and feed per revolution (from a spindle RPM and feed rate you already have).
- Enter the drill diameter and the two remaining values for your chosen mode.
- Optionally open "Estimate feed-only drilling time" to add the hole type, hole depth to full diameter, hole count, drill point angle and any overtravel.
- Optionally open "Add machine limits" to compare the calculated RPM and feed rate against your machine's maximums.
- Review the calculation summary, the formula used, and any warnings shown.
How are drilling speeds and feeds calculated?
Spindle speed comes from the cutting speed and drill diameter, and feed rate comes from the feed per revolution and the spindle speed. This calculator always uses the direct formula for the values entered, on full-precision numbers, rather than chaining through a rounded intermediate result.
- vc = cutting speed (m/min, or SFM in imperial units)
- D = drill diameter (mm, or inches in imperial units)
- Feed rate = feed per revolution × RPM (drilling, not milling's feed-per-tooth × flutes)
- Reverse: cutting speed = (π × D × RPM) ÷ 1,000; feed per revolution = feed rate ÷ RPM
- Point approach = (D ÷ 2) ÷ tan(point angle ÷ 2)
- Feed travel per hole = hole depth + point approach + overtravel
Worked example, metric: a 10 mm drill at a cutting speed of 100 m/min needs RPM = (100 × 1,000) ÷ (π × 10) ≈ 3,183.1 RPM. At a feed per revolution of 0.15 mm/rev, feed rate = 0.15 × 3,183.1 ≈ 477.5 mm/min.
Worked example, imperial: a 0.5 in drill at 300 SFM needs RPM = (300 × 12) ÷ (π × 0.5) ≈ 2,291.8 RPM. At a feed per revolution of 0.006 IPR, feed rate = 0.006 × 2,291.8 ≈ 13.75 IPM.
In reverse, entering a spindle RPM and feed rate gives the cutting speed and feed per revolution those values imply — useful for checking a program or a machine's actual running parameters against the tool manufacturer's application data.
For the optional feed-only time estimate, an 118° point drilling a 10 mm hole with 2 mm of overtravel has a point approach of (10 ÷ 2) ÷ tan(59°) ≈ 3.0 mm, so a 25 mm deep hole has a total feed travel of 25 + 3.0 + 2 ≈ 30.0 mm before the feed rate is applied. A more acute point angle increases the point approach and the feed-only time; a bare tangent-half-angle formula is used regardless of the actual drill geometry beyond that single angle.
Metric and imperial units used
| Quantity | Metric | Imperial | Exact conversion |
|---|---|---|---|
| Diameter / depth / overtravel | mm | in | 1 in = 25.4 mm |
| Cutting speed | m/min | SFM (surface feet per minute) | 1 SFM = 0.3048 m/min |
| Feed per revolution | mm/rev | IPR (inches per revolution) | 1 IPR = 25.4 mm/rev |
| Feed rate | mm/min | IPM (inches per minute) | 1 IPM = 25.4 mm/min |
Every calculation is normalised to millimetres, metres per minute and minutes internally, so switching units converts the figures already entered rather than reinterpreting the same number under a different unit.
What does this calculator assume, and what does it not do?
This calculator covers standard rotating drilling with a single drill, at a fixed diameter, RPM and feed. The feed-only time estimate assumes one continuous feed pass to the entered hole depth, plus the point-approach geometry from the point angle and any overtravel — it does not model peck cycles, retracts, dwell, chip evacuation or any other deep-hole drilling strategy, and "through" versus "blind" hole type changes only the helper copy on the depth field, not the calculation.
It does not calculate torque, thrust, spindle power, tool life, chatter, deflection or hole quality, and it is not an actual CNC cycle time — it excludes rapid approach, retracts, tool changes, machine acceleration and coolant/chip clearing. It does not cover tapping, reaming, boring, counterboring, countersinking, milling, turning or thread milling, and it does not simulate a machine, generate G-code, or draw on a tool or material database. Any warning it shows is a neutral, calculated callout — never a claim that a result is safe, optimal, suitable, manufacturer-approved or guaranteed. Always check the tool manufacturer's guidance, your machine's actual limits, holder condition and runout, coolant, workholding, hole requirements and your shop's procedures before machining.