How do you calculate tapping cycle time?

Divide total thread depth by the tapping feed rate for base time, then multiply by (1 + allowance%). A 24 in total thread depth at 10 in/min gives 2.4 min base; a 30% allowance yields an estimated 3.12 min.

Why is the tapping allowance so high?

Every tapped hole requires the spindle to thread in, decelerate, reverse, and back the tap out, plus rigid-tapping synchronization. That reversal overhead is unavoidable, so allowances of 25-35% are normal, higher than drilling or milling.

How is tapping feed rate determined?

Tapping feed equals spindle RPM times thread pitch, because the tap must advance exactly one pitch per revolution. You cannot freely raise it like a drill feed; it is locked to the thread you are cutting.

What is total thread depth for many tapped holes?

Add the threaded depth of every hole. Sixteen holes each threaded 1.5 inches deep total 24 inches, which is the value you enter, not the depth of one hole.

Tapping vs. thread milling, which is faster?

Tapping is usually faster per hole on small threads but carries reversal overhead and risks tap breakage. Thread milling avoids reversal and broken-tap scrap but takes more passes, so compare both when threads are large or holes are deep.

Why does my tapped part take longer than the estimate?

Short tapped holes have reversal and sync time that rivals the threading time itself. If many holes are shallow, raise the allowance toward 35% so the per-hole overhead is properly counted.

CNC Machining calculator

Tapping Cycle Time Calculator

Tapping cycle time is the spindle-on time to cut internal threads, expanded by an allowance for spindle reversal, synchronization, and retract on each hole. Programmers and estimators use it to quote threaded parts and to account for the surprisingly large overhead that tapping adds, since the tap must thread in, stop, reverse, and back out of every hole. Because tapping feed is locked to thread pitch and the reversal cannot be rushed, this operation often carries the highest allowance of any hole-making process. It is the number that explains why a part with twenty tapped holes costs more than its hole count alone suggests.

What this calculator does

Estimate tapping cycle time from thread depth, tapping feed, and allowance for reversal, synchronization, entry, and retract moves.
estimating tapping cycle time for quoting, routing, capacity planning, or comparing alternate CNC programs
It divides total thread depth by the tapping feed rate for base time, then multiplies by an allowance factor for spindle reversal, synchronization, and retract.

Formula used

Base tapping cycle time = total thread depth ÷ tapping feed rate
Estimated tapping cycle time = base time × allowance factor

Inputs explained

total thread depth: Use the total distance actually traveled in the cutting or feed-controlled portion of the operation.
tapping feed rate: Use the programmed feed for the operation after any process derating or override assumptions.
reversal, sync, and retract allowance: Add allowance for entry, exit, tool changes tied to the operation, chip clearing, positioning, and minor machine delays.

How to use the result

Use it when quoting or planning tapped features where you know cumulative thread depth and the synchronized tapping feed but want a quick cycle estimate including reversal overhead.
It models reversal and sync as a flat allowance, so it can understate parts with many short tapped holes where the per-hole reversal time dominates over the actual threading time.

Current U.S. benchmarks

The producer price index for steel mill products stands at 348.53 (BLS, May 2026), up 6.7% 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

How do you calculate tapping cycle time? Divide total thread depth by the tapping feed rate for base time, then multiply by (1 + allowance%). A 24 in total thread depth at 10 in/min gives 2.4 min base; a 30% allowance yields an estimated 3.12 min.
Why is the tapping allowance so high? Every tapped hole requires the spindle to thread in, decelerate, reverse, and back the tap out, plus rigid-tapping synchronization. That reversal overhead is unavoidable, so allowances of 25-35% are normal, higher than drilling or milling.
How is tapping feed rate determined? Tapping feed equals spindle RPM times thread pitch, because the tap must advance exactly one pitch per revolution. You cannot freely raise it like a drill feed; it is locked to the thread you are cutting.
What is total thread depth for many tapped holes? Add the threaded depth of every hole. Sixteen holes each threaded 1.5 inches deep total 24 inches, which is the value you enter, not the depth of one hole.
Tapping vs. thread milling, which is faster? Tapping is usually faster per hole on small threads but carries reversal overhead and risks tap breakage. Thread milling avoids reversal and broken-tap scrap but takes more passes, so compare both when threads are large or holes are deep.

Last reviewed 2026-05-12.