Does the allowance cover a turret index?

Yes, if the index belongs to this operation. Turret indexing, approach, retract, and chip clearing all sit in the allowance, so the estimate matches the cycle.

Why is the estimate above cut length divided by feed?

Because the ideal division assumes the tool cuts from start to finish with no interruption. The allowance adds the approach, retract, and turret motion every real pass includes.

What allowance fits a shaft with several passes?

Start near 10 to 20 percent, then correct it from the measured cycle time of the first part, since more passes raise it.

Can the gap to target be negative?

Yes. A negative gap means the estimate beats the target you entered and the pass has time in hand before it pressures the schedule.

CNC Machining calculator

Turning Cycle Time Calculator

Work out the cutting time for a turning pass from cut length and feed. The estimate adds an allowance for approach, retract, turret indexing, and chip clearing.

What this calculator does

Estimated turning cycle time from cut length, feed rate, and an allowance for approach, retract, and turret motion.

Formula used

Estimated turning cycle time = turning cut length ÷ turning feed rate × (1 + allowance ÷ 100)
Base turning cycle time = turning cut length ÷ turning feed rate
Allowance added time = base cycle time × allowance ÷ 100
Gap to target = estimated cycle time minus target cycle time

Inputs explained

Turning Cut Length: Total cutting travel along the turning pass.
Turning Feed Rate: Programmed feed for the turning operation.
Approach, Retract, and Turret Allowance: Allowance for approach, retract, turret index, and chip clearing.
Target Cycle Time: Cycle time the turning operation must beat.

How to use the result

Best suited to quoting a turning pass from the CAM path, comparing cycle estimates across lathe programs.
It ignores spindle acceleration, thread passes, and feed changes between roughing and finishing. Tool changes and part load or unload time sit outside this estimate.

Current U.S. benchmarks

The producer price index for steel mill products stands at 381.162 (BLS, Aug 2026), up 23.4% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 17,154 machine shops establishments employing about 223,303 workers (Census County Business Patterns, 2023).

Common questions

Does the allowance cover a turret index? Yes, if the index belongs to this operation. Turret indexing, approach, retract, and chip clearing all sit in the allowance, so the estimate matches the cycle.
Why is the estimate above cut length divided by feed? Because the ideal division assumes the tool cuts from start to finish with no interruption. The allowance adds the approach, retract, and turret motion every real pass includes.
What allowance fits a shaft with several passes? Start near 10 to 20 percent, then correct it from the measured cycle time of the first part, since more passes raise it.
Can the gap to target be negative? Yes. A negative gap means the estimate beats the target you entered and the pass has time in hand before it pressures the schedule.

Last reviewed 2026-10-01.