The basic cycle time equation
Machining time is a straightforward calculation of distance divided by speed. By multiplying the toolpath length for a single pass by the total number of depth passes, you get the total cutting distance. Divide that total by your feed rate, and you have the time spent in the cut.
Machining time = (Path length per pass × number of passes) ÷ Feed rate
The calculation divides the total travel distance of the toolpath by the speed at which the tool is fed through the material.
Worked CNC cycle time example
A CNC router requires 3 passes to cut a 40-inch straight path at a programmed feed rate of 324 inches per minute. The total cutting distance is 120 inches. Dividing 120 by 324 yields an estimated time in the cut of 0.37 minutes, or roughly 22.2 seconds.
Path length40 in
Passes3
Feed rate324 IPM
Time0.37 min
(40 × 3) ÷ 324 = 0.37 minutes
Before you quote the job based on this number
This formula accurately measures time spent moving at the programmed feed rate. However, a mathematically correct time-in-cut is rarely the true cycle time of a finished part.
- RAPIDSThe calculator ignores rapid traverse (G00) movements connecting different cuts.
- ACCELCNC machines do not instantly hit their programmed feed rate. Toolpaths with many tight directional changes will take longer than a long straight cut of the exact same distance.
- CHANGESAdd time for automatic tool changes (ATC), manual tool swaps, spindle spin-up sequences, and touch-offs.
- LOADThe true floor cycle time includes the operator loading stock, clamping, unclamping, and clearing chips.
Important: Use this calculated figure as a baseline for the cutting portion of the job only. Always apply an operational multiplier or measure actual production runs to determine true cycle costs.