Workshop and Metalwork Calculators
Milling feed rate.
Enter the spindle speed (or the surface speed and cutter diameter), the number of flutes and the chip load per tooth from your cutter maker. You get the feed rate in inches and millimetres per minute. Runs in your browser; nothing is sent or stored.
Inputs
Result
Fill the form and press Calculate.
Answer first. Feed rate = RPM x number of teeth x chip load per tooth. The chip load must come from the cutter maker's data for your material; this page does not guess one.
Worked example
A 3-flute end mill at 8,000 RPM with a 0.002 in chip load per tooth: feed = 8,000 x 3 x 0.002 = 48 inches per minute (1219 mm/min). If you only know the cutter is 1/2 in at 400 SFM with 2 flutes and a 0.001 in chip load, RPM comes out at 3,056 and the feed at about 6.1 in/min.
How it works
Formula. FR = RPM x T x CL, where FR is the feed rate (in/min or mm/min), RPM is the spindle speed, T is the number of teeth (flutes) and CL is the chip load, the thickness of the chip each tooth takes. The formula is for cutters on a mill or drill press, not for turning on a lathe, where feed is given per revolution.
No RPM? Leave RPM blank and enter the cutter diameter and surface speed instead; the spindle speed is worked out as RPM = SFM x 12 / (pi x diameter) and then used in the feed formula.
Chip load is your input. Safe chip loads depend on the cutter, material, depth of cut and machine rigidity. Use the table that came with the cutter, and start at the low end of the range. The source notes that insufficient feed on stainless steel can work-harden the part.
Safety. Use a rigid setup, eye protection and guards, and never reach near a turning cutter. If the machine chatters, cuts loudly or smells hot, stop and reduce the feed or depth of cut. This is a general calculation, not professional machining advice.
Sources
- Speeds and feeds - Wikipedia (opened 2026-10-08)
The feed-rate and RPM formulas are from the page above. Conversions use 1 in = 25.4 mm and 1 ft = 0.3048 m.
FAQ
How do I calculate feed rate for milling?
Multiply spindle RPM by the number of flutes and by the chip load per tooth. 8,000 RPM x 3 flutes x 0.002 in = 48 in/min.
What is chip load?
The thickness of material removed by each tooth per revolution. It is also called feed per tooth. Cutter makers publish recommended values by material and diameter.
Does the number of flutes change the feed rate?
Yes. At the same chip load per tooth, a 4-flute cutter can be fed twice as fast as a 2-flute cutter.
Can I use this for a lathe?
No. The source states the formula is not for lathe turning, where feed rate is given in distance per spindle revolution.
What is the feed per revolution shown?
Flutes multiplied by chip load: the distance the cutter advances during one turn of the spindle.