Maker and DIY Calculators
CNC material removal rate.
MRR is how much material your cutter removes per minute. Use it to compare cutting strategies, and to estimate how long a roughing pass on a pocket takes.
MRR = width of cut x depth of cut x feed rate. A 3 mm stepover, 2 mm depth and 800 mm/min feed removes 4.8 cm3 per minute, so a 100 x 60 x 10 mm pocket (60 cm3) takes about 12.5 minutes to rough.
Cut and pocket
Removal rate
Fill the form and press Calculate.
Worked example
MRR = 3 mm x 2 mm x 800 mm/min = 4,800 mm3/min = 4.8 cm3/min. A pocket 100 x 60 x 10 mm holds 60,000 mm3 = 60 cm3, so roughing takes 60 / 4.8 = 12.5 minutes in 5 depth passes of 2 mm. In imperial, 0.12 in x 0.08 in x 30 in/min is 0.288 in3/min.
How it works
Material removal rate is the volume of material removed per unit time. In milling it equals the width of the cut times the depth of the cut times the feed rate. Dividing a pocket's volume by the MRR gives the time at that rate; the number of depth passes is the pocket depth divided by the depth of cut, rounded up.
Not included. Whether your spindle and tool can sustain the MRR, chip thinning, corners and acceleration, plunge or ramp moves, rapid moves, and finishing passes. Use feeds and speeds from the cutter maker; the CNC feeds and speeds calculator turns them into RPM and feed.
Sources (opened 2026-10-08). Material removal rate - Wikipedia for the definition of material removal rate as the volume of material removed per minute in machining operations such as milling; Speeds and feeds - Wikipedia for the statement that cutting speed, feed rate and depth of cut together determine the material removal rate. The multiplication formula is straight geometry, and the example values are placeholders.
FAQ
What is material removal rate?
It is the volume of material a machining operation removes per minute. In milling it is the width of cut times the depth of cut times the feed rate.
How do I estimate the time to rough a pocket?
Divide the pocket volume by the MRR. The result is an ideal straight-line time; add time for corners, ramps, rapids and finishing.
Is a higher MRR always better?
No. It is limited by spindle power, tool strength, rigidity and finish. Use it to compare strategies, not as a target by itself.
What stepover and depth should I use?
Use the values your cutter maker recommends for your material and machine. This calculator only does the arithmetic on the values you enter.
Why is my real time longer?
The estimate assumes the cutter is always fully engaged at the entered feed rate. Real programs slow at corners, change direction, retract and make finishing passes.
Disclaimer
Estimates from the numbers you enter. Machining can cause serious injury; use proper guarding, eye protection and work holding. Rates here are arithmetic, not machine-specific advice.