01
Formula
RPM = SFM × 12 ÷ (π × diameter).
Feed in inches per minute = RPM × flutes × chip load. Cutting speed in SFM = π × diameter × RPM ÷ 12. A drill speed calculator is that RPM formula with the drill diameter.
Apply for financingFeeds and speeds
Feeds and speeds calculator for RPM and feed
This feeds and speeds calculator turns surface feet per minute and a tool diameter into RPM, then into inches per minute from flute count and chip load. The same math is a speeds and feeds calculator, a cnc feeds and speeds calculator, a cutting speed calculator, a drill speed calculator, and a machining calculator. The cutting speed you should run is a tooling decision. This page does the arithmetic.
Find
Feed
36.67in/min
RPM2,292
Surface speed300 SFM
Chip load0.0040 in
Planning estimate from the numbers you enter. Coverage, density, waste and price are assumptions, not a supplier quote or an engineering specification.
How it works
RPM comes from surface speed and diameter. Feed comes from RPM and chip load.
RPM equals surface feet per minute times 12, divided by pi times diameter in inches. Inches per minute equal RPM times flutes times chip load. A half-inch tool at 300 surface feet, 4 flutes, and 0.004 inch chip load runs at 2,291.83 RPM and 36.67 inches per minute. Switch to cutting speed and enter RPM instead: surface feet equal pi times diameter times RPM, divided by 12. A drill uses the same RPM formula. Two flutes and a smaller chip load are typical. The page will not pick a surface speed for a material. Use the speed the toolmaker published, then calculate.
02
Example
0.5 inch tool, 300 SFM, 4 flutes, 0.004 inch chip.
RPM is 2,291.83 and the feed is 36.67 inches per minute. Those are the fields already filled in. The cnc feeds and speeds calculator result is only as good as the surface speed and the chip load you trust.
03
Tips
Diameter is the cutting diameter, not the shank.
A 0.5 inch end mill and a 0.5 inch drill do not share a chip load. Start from the toolmaker's chart for the material. This machining calculator does not apply a tool-life derate unless you lower the surface speed yourself.
04
Equipment
The mill or the lathe is the purchase.
Dengaro arranges financing for a CNC or another machine tool. The speeds are not a loan amount.
Important questions
Know what to expect.
Why do feeds and speeds and speeds and feeds use one page?+
They are the same pair of numbers. Surface speed sets RPM. Chip load sets the feed. The phrase order does not change the formula.
How is the cutting speed calculator different?+
Switch the control to cutting speed. You enter RPM and diameter, and the page returns surface feet per minute. The other mode starts from surface feet and returns RPM and feed.
What chip load should a drill use?+
The drill speed calculator still needs a chip load you choose. A twist drill is often two flutes. Use the feed per revolution the drill maker lists, and type that as the chip load.
Does this set the machine?+
No. It is planning math. The program, the holder, and the material still decide what is safe.
Financing built into the sale