Material Cost Per Part Calculator

Calculate total cost per injection-molded part including material (with runner waste and regrind), machine time, and overhead. Shows cost breakdown percentages.

Inputs

Part weight (g)

Resin price ($/kg)

Cycle time (sec)

Number of cavities

Machine rate ($/hr)

Runner waste (%)

Regrind recovery (%)

Scrap rate (%)

Overhead rate ($/hr)

Tab to move between fields

Results

Total cost per part ($)

$0.73

Material cost per part ($)$0.06

Machine cost per part ($)$0.50

Overhead cost per part ($)$0.17

Material %8.9

Machine %68.4

Overhead %22.8

Parts per hour120

Cost per 1,000 parts ($)$731.46

Effective material per part (g)25.92

How to Use This Calculator

Enter Part weight (g), Resin price ($/kg), and Cycle time (sec).
Set Number of cavities, Machine rate ($/hr), and Runner waste (%).
Adjust Regrind recovery (%), Scrap rate (%) as needed.
Review the Total cost per part ($) ($) result.
Use Material cost per part ($) ($) and Machine cost per part ($) ($) to inform your decision.

How the result changes with Cycle time (sec)

Cycle time (sec)	Total cost per part ($)
61	$1.42
211	$4.75
390	$8.73
540	$12.06

What each input means

Part weight (g): Net weight of the finished part in grams.
Resin price ($/kg): Material cost per kilogram of virgin resin.
Cycle time (sec): Total injection molding cycle time in seconds.
Number of cavities: Number of cavities in the mold.
Machine rate ($/hr): Fully burdened machine hourly rate.
Runner waste (%): Runner/sprue weight as % of part weight. 0% for hot runner.
Regrind recovery (%): Percentage of runner waste that can be regrind and reused.
Scrap rate (%): Percentage of parts rejected as scrap.
Overhead rate ($/hr): Labor, facility, and quality overhead per hour.

What each result means

Total cost per part ($): Sum of material, machine, and overhead costs per good part.
Material cost per part ($): Material cost including waste and scrap allowance.
Machine cost per part ($): Machine time cost per part.
Overhead cost per part ($): Labor and facility overhead per part.
Material %: Material cost as percentage of total.
Machine %: Machine cost as percentage of total.
Overhead %: Overhead as percentage of total.
Parts per hour: Production rate considering cavities and cycle time.
Cost per 1,000 parts ($): Total cost for a batch of 1,000 good parts.
Effective material per part (g): Actual material consumed per good part including waste.

How this is calculated

Worked example, using the default values

Identify Input Parameters
4 parameters
Part weight (g) = 25, Resin price ($/kg) = 2.5, Cycle time (sec) = 30, Number of cavities = 1 = 9 input(s) provided
Calculate Total cost per part
Total cost per part = materialCostPerPart + machineCostPerPart + overheadCostPerPart
0.7315 = $0.732
Calculate Material cost per part
Material cost per part = (effectiveMaterialG / 1000) * resinPricePerKg
0.0648 = $0.065
Calculate Machine cost per part
0.5 = $0.5

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