An injection molding estimate should distinguish the tool investment from the cost of each production run. Otherwise, a low per-part figure can hide an unrecovered mold cost, or a repeat order can be charged for tooling that the customer has already paid for.
The worksheet below provides a calculation for a defined process plan. It is not an interactive calculator or an automatic mold-design estimate. All example rates are illustrative and should be replaced with validated inputs from your shop and suppliers.
Establish the production assumptions
Collect the current model and drawing, resin grade, color, finish, required quantity, expected releases, inspection requirements, and delivery schedule. Confirm the mold concept, active cavity count, cycle time, and the machine suitable for that tool.
Record whether the quoted quantity is a firm order or an annual forecast. Amortizing tooling over a forecast creates a commercial risk if the customer purchases fewer parts. Make that agreement explicit.
Calculate machine time from cycles
For a simple model with identical parts in each active cavity:
Expected good parts per cycle = active cavities × expected yield
Required cycles = round up(order quantity ÷ expected good parts per cycle)
Running hours = required cycles × cycle seconds ÷ 3,600
Machine cost = running hours × hourly machine rate
Expected yield is a planning assumption, not a guarantee of the final accepted quantity. Separate startup scrap and setup time where they are not included in the yield or cycle estimate. A family mold with different parts requires a more detailed allocation.
Use the complete cycle time, including the steps required before the next cycle can begin. Ask an experienced process engineer to validate assumptions for a new tool. A CAD model alone does not establish the production cycle.
Price material and labor without duplication
Estimate the purchased resin consumed by the job, including the relevant runners, purge, and losses. Do not assume all waste can be reused or credited at its original purchase price. Reuse must be compatible with the process and customer specification.
Define whether the machine rate includes an operator or overhead. Add labor and overhead separately only when they are excluded. Include any secondary operations, inspection, packaging, outsourced work, and transport that belong in the quote.
Worked example: 10,000 parts
Assume a two-cavity mold, a 30-second cycle, and 100% yield solely to keep this example easy to follow. Production needs 5,000 cycles, or 41.6667 running hours. Real estimating should use the shop's expected yield and startup allowances.
- Tooling; Calculation: Separate upfront amount; Estimated cost: €12,000
- Run setup; Calculation: Fixed for this release; Estimated cost: €300
- Material; Calculation: 250 kg consumed × €4/kg; Estimated cost: €1,000
- Machine; Calculation: 41.6667 hours × €60/hour; Estimated cost: €2,500
- Separate labor, inspection, packing; Calculation: 10,000 × €0.15; Estimated cost: €1,500
- Production cost, excluding tooling; Estimated cost: €5,300
- First-order cost, including tooling; Estimated cost: €17,300
Production cost is €0.53 per part. If all tooling is allocated to these 10,000 parts, tooling adds €1.20, giving €1.73 per part before margin, shipping, and tax.
A repeat run using the paid-for tool would start from the production calculation, with any maintenance, repair, or change costs considered separately. Do not present the first-order all-in cost as if it were the recurring unit cost.
Test the sensitivity before sending the quote
Change one assumption at a time. If cycle time is 36 seconds rather than 30, the same simplified job needs 50 running hours. At €60 per hour, machine cost increases by €500. If only one cavity can run, the number of cycles doubles at the same yield.
These checks show which assumptions deserve validation before you commit. Also review the consequences of multiple delivery releases, tool maintenance, rejected parts, and a change in resin price.
Turn the estimate into a commercial offer
Show tooling and recurring production prices clearly. Specify what tooling changes, trials, inspection, and maintenance are included. Apply your pricing policy to the defined cost base; a 30% target margin, for example, uses cost ÷ 0.70, not cost × 1.30.
New mold concepts, uncertain cycle times, or unconfirmed inspection requirements should remain subject to review. A repeat order for an established part is a stronger candidate for a maintained price than a new design with unresolved tooling assumptions.
Put repeatable logic into your system
Phasio provides injection molding quoting and production software. Its configurable pricing workflow can reflect the assumptions and commercial rules you establish; it is not a claim that Phasio designs the mold or simulates resin flow.
Start with the questions to answer before building an equation. Validate the estimate against completed work, give staff a clear review path, and recheck calculations whenever tooling, cycle time, quantity, or the customer's requirements change.
READY TO TRY PHASIO?
See how Phasio transforms manufacturing workflows
From instant quoting to order management, explore the platform and get hands-on in minutes.