Why is the tapping allowance often large?

A tap cuts on the way in and reverses to break the chip, so the spindle spends time not making thread. Reversal and synchronization often rival the cutting time on short threads.

Does feed per revolution belong in this calculator?

No. Enter the programmed feed in inches per minute. A tap's feed per revolution equals its pitch, so convert pitch times spindle speed to in/min first.

Should the depth include the chamfer and lead?

Add the lead and breakthrough travel to the thread depth, because the tap travels that distance inside the cycle before it retracts.

What is a typical reversal and sync allowance?

Start near 25 to 35 percent for rigid tapping, then adjust from the cycle time of the first proven hole; deep holes and slower spindles run higher.

CNC Machining calculator

Tapping Cycle Time Calculator

Estimate the time to tap a pattern from total thread depth and feed. The allowance prices spindle reversal, synchronization, and retracts, which dominate a tapping cycle.

What this calculator does

Estimated tapping cycle time from total thread depth, feed rate, and an allowance for reversal, synchronization, and retract.

Formula used

Estimated tapping cycle time = total thread depth ÷ tapping feed rate × (1 + allowance ÷ 100)
Base tapping cycle time = total thread depth ÷ tapping feed rate
Allowance added time = base cycle time × allowance ÷ 100
Gap to target = estimated cycle time minus target cycle time

Inputs explained

Total Thread Depth: Combined thread depth across all tapped holes.
Tapping Feed Rate: Programmed tapping feed in inches per minute.
Reversal, Sync, and Retract Allowance: Allowance for spindle reversal, synchronization, and retract.
Target Cycle Time: Cycle time the tapping operation must beat.

How to use the result

Best suited to quoting a tapped hole pattern, comparing rigid and tension-compression tapping.
It assumes the tap reverses once per hole; chip-breaking cycles add reversal time. Tool changes, dwell, and fixture moves are outside the 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

Why is the tapping allowance often large? A tap cuts on the way in and reverses to break the chip, so the spindle spends time not making thread. Reversal and synchronization often rival the cutting time on short threads.
Does feed per revolution belong in this calculator? No. Enter the programmed feed in inches per minute. A tap's feed per revolution equals its pitch, so convert pitch times spindle speed to in/min first.
Should the depth include the chamfer and lead? Add the lead and breakthrough travel to the thread depth, because the tap travels that distance inside the cycle before it retracts.
What is a typical reversal and sync allowance? Start near 25 to 35 percent for rigid tapping, then adjust from the cycle time of the first proven hole; deep holes and slower spindles run higher.

Last reviewed 2026-10-01.