Drill Speed (RPM)
Find the recommended drill RPM for a bit and material.
About Drill Speed (RPM)
Drill speed depends on both the bit size and the material's recommended cutting speed. Smaller bits and harder materials call for higher and lower RPM respectively. Running a bit at the wrong speed overheats or breaks it, so matching RPM to material avoids ruining expensive drill bits.
Formula
Drill Speed (RPM)
RPM = surface speed x 3.82 / bit diameter
- surface speed
- Feet per minute the bit edge travels
Worked example
With the default values below, Drill Speed (RPM) returns Recommended RPM of 7,640. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Bit diameterminimum 0.01 in
- 0.25 in
- Materialone of Wood, Aluminum, Steel, Stainless steel, Plastic
- Wood
Results
- Surface Speed
- 500 sfm
- Recommended RPM
- 7,640
- RPM Range Low
- 6,112
- RPM Range High
- 9,168
Step by step
- 1Values used
- 2Drill Speed (RPM)
- 3Recommended RPM= 7,640
- 4Surface Speed= 500 sfm
- 5RPM Range Low= 6,112
- 6RPM Range High= 9,168
Assumptions and limits
- The result is derived only from the 2 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
- Figures are rounded for display to whole numbers, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Drill Speed (RPM) calculated?
RPM = surface speed x 3.82 / bit diameter Drill speed depends on both the bit size and the material's recommended cutting speed. Smaller bits and harder materials call for higher and lower RPM respectively.
Why does Drill Speed (RPM) matter?
Running a bit at the wrong speed overheats or breaks it, so matching RPM to material avoids ruining expensive drill bits.
What values do I need to enter?
This calculator takes 2 inputs: Bit diameter, Material. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.