Injection Molding Unit Cost Breakdown Calculator
This calculator determines the unit cost of plastic injection molded parts. The logic incorporates core manufacturing principles:
- Material Cost: Calculated by part weight, material price (e.g., PP, PE, ABS, PC), runner weight per shot, and regrind recovery percentage.
- Machine Time Cost: Amortized by hourly machine rate, cycle time, and the number of cavities in the mold.
- Labor Cost: Calculated based on operator hourly rate divided by press output.
- Quality & Overhead: Includes scrap defect rate percentages and facility overhead ratios.
- Mold Amortization: Tooling cost divided by the total expected lifetime parts.
COST BREAKDOWN v2
Unit Cost Breakdown & What-If Analyzer
liveMaterial & product
Part weight (g)
g
Runner weight (g/shot)
g
Total per shot, shared across all cavities
Material price (USD/kg)
$/kg
Regrind recovery (%)
60%
Runner recovered at 60% of virgin price
Machine & process
Machine rate (USD/hr)
$/hr
Labor rate (USD/hr)
$/hr
Set 0 for fully automated cell
Cycle time (s/shot)
s
Number of cavities
cav
Quality & overhead
Scrap / defect rate (%)
2.0%
World-class: <0.5% · Typical: 1–3% · Poor: >5%
Overhead / admin rate (%)
18%
Covers facility, utilities, admin on top of variable costs
Mold amortization (USD/pc)
$/pc
Mold cost ÷ lifetime parts. Set 0 to exclude.
Unit cost per good part
0.2543USD/pc
Cost / 1K pcs
$254
Output
4/shot
Pcs/hr
514
Mat% of total
22%
Cost composition — proportional waterfall
Optimization opportunities — ranked by cost impact
Cycle time
Base: 28s
28s
Cavities
Base: 4
4
Part weight
Base: 25g
25g
Material price
Base: $2.20/kg
$2.2
Scrap rate
Base: 2.0%
2.0%
Machine rate
Base: $65/hr
$65