Milling Speeds and Feeds Calculator
Use this milling speeds and feeds calculator to estimate spindle speed and table feed from cutting speed, cutter diameter, effective teeth, and feed per tooth. You can enter metric or US customary values. The calculator converts inputs to a metric calculation internally and converts the displayed result back to your selected units.
The output is a starting calculation. It is not a recommendation for a material or a specific tool. Use cutting data from the tool manufacturer and confirm that the machine, holder, workholding, and setup can support the cut.
Interactive calculator
Enter values and select Calculate.
How the calculation works
Spindle speed depends on cutting speed and the cutter’s effective diameter:
n = 1000 × vc / (π × D)
Here, n is spindle speed in revolutions per minute, vc is cutting speed in metres per minute, and D is cutter diameter in millimetres. The factor 1000 converts metres to millimetres.
Table feed depends on spindle speed, the number of effective teeth, and feed per tooth:
vf = n × z × fz
Here, vf is feed in millimetres per minute, z is the number of effective teeth, and fz is feed per tooth in millimetres. If you enter a machine RPM limit, the calculator caps the calculated speed and recalculates feed from that capped RPM.
Worked example
For a 10 mm cutter at 120 m/min, the uncapped spindle speed is about 3,820 rpm. With four effective teeth and a chip load of 0.05 mm per tooth, the feed is about 764 mm/min. If the machine is limited to 3,000 rpm, the estimated feed becomes 600 mm/min and the actual cutting speed falls to about 94.2 m/min.
Choose inputs from the tool data
Use the tool maker’s recommended cutting speed and chip load for the material, cutter type, engagement, and setup. Enter the effective diameter at the cutting depth where the tool geometry requires it. Ball-nose tools, tapered cutters, and some insert geometries do not always cut at their nominal diameter.
The formula assumes a steady milling cut. It does not calculate radial chip thinning, engagement effects, power, torque, deflection, chatter, coolant requirements, or tool life. It also does not select a safe value for your machine.
For material removal rate at a chosen depth and width of cut, use the milling material removal rate calculator. For published cutting-formula definitions, see Sandvik Coromant’s milling formulas.
