Machining Time Calculator

Turning a 200 mm length at 0.2 mm/rev and 800 RPM takes 1 min 15 sec (table feed 160 mm/min).

The formulas

What the calculator gives you

This is the cutting time only — the time the tool is engaged in the workpiece for one pass at constant feed. Real cycle time adds rapid traverses, tool changes, spindle ramp-up, and any dwell or coolant-on delays. For a first-cut estimate, add 15–25% to the pure cutting time to account for non-cutting moves on a CNC.

Approach and overtravel

In turning, add one tool-nose radius to the cut length for approach and the same for overtravel if the tool must clear the shoulder. In milling, add the cutter radius (for peripheral cuts) or the full cutter diameter (for slotting) to the programmed length — the cutter must fully engage before steady-state chip load is reached. Drilling adds a cone height of d/(2×tan(θ/2)) for the drill point, where θ is the point angle (typically 118° or 135°).

Multiple passes

If the total stock removal requires more than one pass, multiply the single-pass time by the number of passes and add rapid-return time between passes. For roughing followed by a finish pass, calculate each separately — they will have different feeds and speeds.