CNC Machining Calculators
Free tools for cutting speed, spindle speed, feed rate and material removal rate. Nothing to install, nothing to sign up for. We use these calculations every day in our own shop in Ankara.
These calculators do the arithmetic only. Cutting speed and feed values depend on the material, the tool, the coolant and the rigidity of the setup — always use the values recommended by your tool supplier.
Milling
Enter tool diameter and cutting speed to get spindle speed. Add teeth and feed per tooth for feed rate, then depths of cut for material removal rate.
n = Vc × 1000 / (π × D) · Vf = fz × z × n · Q = ae × ap × Vf / 1000Turning
Enter workpiece diameter and cutting speed to get spindle speed, then feed per revolution for feed rate.
n = Vc × 1000 / (π × D) · Vf = f × nDrilling
Enter drill diameter and cutting speed to get spindle speed, then feed per revolution for feed rate.
n = Vc × 1000 / (π × D) · Vf = f × nISO 2768 general tolerance
Shows the deviation the standard allows for a dimension left untoleranced on the drawing. Enter the size and see all four classes at once.
Material weight
Calculates the weight of a block, bar or tube. Useful for shipping, raw material cost and quoting.
kg = cm³ × g/cm³ / 1000 · Densities are typical handbook values; for an exact figure use the material certificate.Ra to N grade
Older drawings carry an N grade instead of an Ra value. This converts between the two.
Unit converter
Frequently asked questions
How do I calculate spindle speed from cutting speed?
Spindle speed n (rpm) = Vc × 1000 / (π × D), where Vc is the cutting speed in metres per minute and D is the diameter in millimetres. For milling, D is the tool diameter; for turning, it is the workpiece diameter.
How do I calculate feed rate for milling?
Feed rate Vf (mm/min) = fz × z × n, where fz is feed per tooth in millimetres, z is the number of teeth on the cutter and n is the spindle speed in rpm.
How is material removal rate calculated?
For milling, Q (cm³/min) = ae × ap × Vf / 1000, where ae is the radial depth of cut, ap the axial depth of cut, both in millimetres, and Vf the feed rate in mm/min.
How do I convert m/min to SFM?
Multiply metres per minute by 3.2808 to get surface feet per minute. To go the other way, divide SFM by 3.2808.
What does ISO 2768-mK mean on a drawing?
The "m" sets the medium class for dimensional features and the "K" the medium class for geometrical tolerances. Every dimension without its own tolerance then takes its value from the ISO 2768-1 class m table. The calculator above shows all four classes for a given size.
Does the general tolerance apply below 0.5 mm?
No. The ISO 2768-1 table starts at 0.5 mm; below that the tolerance has to be written next to the dimension on the drawing.
Which cutting speed should I use?
That depends on the material, the tool grade and coating, the coolant and how rigid the setup is. These calculators do not recommend values; use the data sheet from your tool supplier and adjust from there.
Need the part made, not just the numbers?
We machine precision parts on 5-axis and Swiss-type machines in Ankara, Türkiye. Send your technical drawing and we will review it for manufacturability and quote it.
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