How do you calculate mold amortization per part?

Multiply the mold investment by a maintenance adder, then divide by the expected lifetime volume. For an $85,000 mold with a 1.10 maintenance adder over 500,000 parts, the per-part tooling cost is small and gets added to material and conversion cost in the quote.

What is a maintenance cost adder?

It is a multiplier above 1.0 that grosses up the mold cost for expected repairs and refurbishment over its life. Typical values are 1.05 to 1.20, higher for abrasive glass-filled resins or complex tools with many moving cores.

How do I estimate lifetime mold volume?

Base it on the mold steel and resin abrasiveness: a P20 mold may last around 500,000 shots while a hardened H13 tool can exceed a million. Multiply expected shots by cavity count and discount for the program's realistic life.

Prototype mold vs production mold: how does volume decide?

At low volume a cheap aluminum or P20 prototype mold amortizes to less per part even though it wears out sooner; at high volume a hardened tool's higher cost spreads thin and its longer life wins. Run both through this calculator at your real volume to see the crossover.

Should amortization be in the part price or quoted separately?

Both are common. Some customers pay tooling up front, removing amortization from the piece price; others want it amortized into the part price over a volume commitment. This calculator gives the per-part figure for the amortized option.

What if the program ends before lifetime volume is reached?

Then each part absorbed less tooling cost than planned and the mold isn't fully paid off. To protect against that, amortize over a conservative committed volume rather than the optimistic maximum mold life.

Injection Molding calculator

Mold Amortization Cost Calculator

Mold amortization cost is the slice of tooling investment assigned to each molded part, found by spreading the full mold cost plus lifetime maintenance across the total parts the tool will ever produce. Estimators and program managers fold it into a quote alongside material and conversion cost so the tooling pays for itself over the program. It matters because under-amortizing leaves the tool unpaid for at end of life, while over-amortizing makes the quote uncompetitive. It is also the deciding number when choosing between a low-cost prototype mold and a hardened production tool, since the right choice depends entirely on lifetime volume.

What this calculator does

Calculate the tooling cost amortized per part from total mold investment and expected lifetime production volume.
Use this when quoting part prices, comparing tooling options (single vs. multi-cavity), or deciding between a production mold and a prototype mold based on volume requirements.
It computes the amortized tooling cost per part by spreading the mold investment, grossed up for maintenance, across the expected lifetime volume.

Formula used

Amortized cost per part = (Mold investment x Maintenance adder) / Lifetime volume
Add this to material and conversion cost for total part cost

Inputs explained

Total mold investment:
Expected lifetime production volume:
Maintenance cost adder:

How to use the result

Use it when quoting a part price, comparing single-cavity versus multi-cavity tooling, or deciding between a prototype mold and a production mold based on program volume.
It assumes the full lifetime volume is actually produced; if the program ends early, the real per-part cost is higher because fewer parts absorbed the tooling cost.

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 9,635 plastics product manufacturing establishments employing about 677,302 workers (Census County Business Patterns, 2023).

Common questions

How do you calculate mold amortization per part? Multiply the mold investment by a maintenance adder, then divide by the expected lifetime volume. For an $85,000 mold with a 1.10 maintenance adder over 500,000 parts, the per-part tooling cost is small and gets added to material and conversion cost in the quote.
What is a maintenance cost adder? It is a multiplier above 1.0 that grosses up the mold cost for expected repairs and refurbishment over its life. Typical values are 1.05 to 1.20, higher for abrasive glass-filled resins or complex tools with many moving cores.
How do I estimate lifetime mold volume? Base it on the mold steel and resin abrasiveness: a P20 mold may last around 500,000 shots while a hardened H13 tool can exceed a million. Multiply expected shots by cavity count and discount for the program's realistic life.
Prototype mold vs production mold: how does volume decide? At low volume a cheap aluminum or P20 prototype mold amortizes to less per part even though it wears out sooner; at high volume a hardened tool's higher cost spreads thin and its longer life wins. Run both through this calculator at your real volume to see the crossover.
Should amortization be in the part price or quoted separately? Both are common. Some customers pay tooling up front, removing amortization from the piece price; others want it amortized into the part price over a volume commitment. This calculator gives the per-part figure for the amortized option.

Last reviewed 2026-05-12.