How do you calculate good parts from mold cavitation?

Multiply cavity count by the mold's rated shots for gross parts, then multiply by machine uptime and first-pass yield. With 4 cavities over 480 shots at 90% uptime and 97% yield, good capacity is 4 x 480 x 0.90 x 0.97 = 1,676 good parts.

Is a higher cavitation mold worth the extra cost?

Higher cavitation raises output per shot but also mold price and complexity. Run both cavity counts through this calculator, amortize each mold's cost over its good capacity, and pick the one with the lower fully-loaded cost per good part — not simply the most cavities.

What is the difference between shots and good parts?

Shots are machine cycles; parts are cavities times shots. Here 4 cavities x 480 shots gives 1,920 gross parts, but after 90% uptime and 97% yield only 1,676 are salable — the 244-part gap is what cavitation math on paper misses.

Why does first-pass yield matter in mold economics?

Shorts, flash, sink and contamination scrap parts without adding shot life back. At 97% yield the mold loses 51.8 parts' worth of output over the interval, so a mold that runs a low-yield resin needs more shots to hit the same good-part target.

How many shots does an injection mold last?

It ranges from tens of thousands for a soft prototype tool to millions for a hardened production mold; the 480 in the example is a service interval, not total life. Enter shots to your next scheduled maintenance to plan the parts bank between services.

How do I set a mold maintenance interval?

Use good part capacity — 1,676 here — to time PM so the mold comes out for cleaning with a fresh good-part run already banked. Basing PM on gross shots ignores the downtime and scrap that shrink the real output between services.

Tooling, Fixtures, Dies & Mold Economics calculator

Mold Cavitation Economics Calculator

Mold cavitation economics translates a mold's cavity count and rated shot life into the good molded parts it will actually produce, so you can judge whether a higher-cavitation tool pays for itself. Injection molding process engineers, tooling buyers and program managers use it to compare a 2-cavity versus 4-cavity build, schedule mold maintenance, and set the tooling amortization on a molded part. It matters because cavity count multiplies both output and mold cost — the economics only work if uptime and yield hold across all cavities. This calculator strips the theoretical shot count down to shippable parts so the cavitation decision rests on real capacity.

What this calculator does

Estimate mold cavitation economics for tooling, fixtures, dies and mold economics using production-ready inputs so teams can confirm whether capacity can cover demand before committing the schedule.
Use it when mold cavitation economics in tooling, fixtures, dies and mold economics is being asked to take on more work and you need to know if there is room.
It multiplies cavity count by rated mold shots to get gross capacity, then derates for molding machine uptime and molded-part first-pass yield to give good part capacity.

Formula used

Gross mold cavitation economics capacity = mold cavitation economics output per cycle × available mold cavitation economics cycles
Good mold cavitation economics capacity = gross capacity × expected mold cavitation economics uptime × expected mold cavitation economics first-pass yield

Inputs explained

Parts per mold shot (cavity count):
Rated mold shots before service:
Molding machine uptime:
Molded part first-pass yield:

How to use the result

Use it when justifying cavity count on a new mold, planning a preventive-maintenance shot interval, or amortizing mold cost per good part.
It assumes every cavity runs and yields equally; a blocked or short-filling cavity, or family-mold imbalance, will make real good output fall below the estimate.

Current U.S. benchmarks

The producer price index for plastic resins and materials stands at 319.371 (BLS, May 2026), up 19.5% from a year earlier. Quotes priced off last quarter's material cost miss this move.
The U.S. has 14,378 furniture and related products establishments employing about 355,594 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate good parts from mold cavitation? Multiply cavity count by the mold's rated shots for gross parts, then multiply by machine uptime and first-pass yield. With 4 cavities over 480 shots at 90% uptime and 97% yield, good capacity is 4 x 480 x 0.90 x 0.97 = 1,676 good parts.
Is a higher cavitation mold worth the extra cost? Higher cavitation raises output per shot but also mold price and complexity. Run both cavity counts through this calculator, amortize each mold's cost over its good capacity, and pick the one with the lower fully-loaded cost per good part — not simply the most cavities.
What is the difference between shots and good parts? Shots are machine cycles; parts are cavities times shots. Here 4 cavities x 480 shots gives 1,920 gross parts, but after 90% uptime and 97% yield only 1,676 are salable — the 244-part gap is what cavitation math on paper misses.
Why does first-pass yield matter in mold economics? Shorts, flash, sink and contamination scrap parts without adding shot life back. At 97% yield the mold loses 51.8 parts' worth of output over the interval, so a mold that runs a low-yield resin needs more shots to hit the same good-part target.
How many shots does an injection mold last? It ranges from tens of thousands for a soft prototype tool to millions for a hardened production mold; the 480 in the example is a service interval, not total life. Enter shots to your next scheduled maintenance to plan the parts bank between services.

Last reviewed 2026-05-12.