Understand Plastic Injection-Molding Price Calculations to Set Realistic Budgets

Sticker shock often comes from not knowing how the quote was built. By breaking down every cost driver—tooling, material, machine time, labor, and overhead—you can predict spend, benchmark suppliers, and negotiate confidently. The framework below explains each element in a standard plastic injection-molding price calculation and shows how to tweak variables to hit your target budget without compromising quality.

1 The Two Big Buckets

Cost Bucket	Typical Share of Unit Price	Notes
Non-Recurring Engineering (NRE)	50–100 % of first-order spend	Tool design, mold construction, sampling
Recurring Production Cost (RPC)	100 % of every piece thereafter	Resin, machine time, overhead, packaging

Rule of thumb: On volumes below ~10 000 pieces, NRE often dominates. Above 50 000, RPC drives TCO.

2 Tooling Cost (NRE)

Driver	Impact	Mitigation
Steel Choice (Al, P20, H13)	Harder steel = longer life, higher cost	Use aluminium prototype, credit toward steel upgrade
Cavity Count	More cavities raise upfront cost but lower unit price	Run break-even analysis vs. annual demand
Complexity (slides, lifters, hot runners)	Each added action +5–15 %	Consider hand-loaded inserts for short runs
Surface Finish (SPI-A vs. VDI)	Mirror polish adds hours of manual work	Texture areas not in the cosmetic zone

Quick estimate formula:

Tool Cost ≈ (Base Steel + Machining Hours × Shop Rate) × Complexity Factor

Complexity factor ranges 1.1–1.6 depending on lifters, hot runner, and mirror polish.

3 Material Cost (RPC)

Equation:

Material $/pc = Shot Weight (g) × Resin $/kg ÷ 1000

Include runners unless you use a hot-runner or regrind policy.
Example: 50 g shot × US $2.20/kg = US $0.11/piece

4 Machine (Press-Time) Cost

Variable	Typical Value	How to Lower
Cycle Time	20–65 s	Conformal cooling, gate optimization
Press Rate	US $35–90/h depending on tonnage & region	Smaller press via optimized clamp force
Utilization	70–85 %	Scientific molding to reduce downtime

Press Cost/pc = (Cycle Time ÷ 3600) × Press Rate

5 Labor & Overhead

Setup Labor: amortized over the lot; high for short runs.
QC & Packaging: vision inspection, manual insert, or blister pack adds US $0.02–0.25/pc.
Plant Overhead: utilities, depreciation—typically loaded into the press rate in Asia.

6 Scrap & Yield

Startup & Purge Loss: 2–5 % of first shots; hot runners reduce this.
Regrind Allowance: ≤ 15 % for ABS/PP; saves resin but monitor color & IV.

Add scrap buffer: (Material + Press Cost) × Scrap %.

7 All-In Unit-Price Model

Unit Price = (Material + Press + Labor + Packaging + Scrap Buffer) 
           + Tool Amortization / Lot Size

Tool amortization = Tool Cost ÷ expected lifetime pieces (or by months for accounting).

8 Example—ABS Housing, 30 000 Pieces/Year

Element	Value	Cost/pc
Shot Weight	48 g	—
Resin ABS	US $2.35/kg	US $0.11
Cycle Time	28 s, 200 t press @ US $55/h	US $0.43
Labor/QC	—	US $0.06
Packaging	—	US $0.04
Scrap 3 %	—	US $0.02
Tool Cost	US $22 000 (P20, 2-cavity)	US $0.37 (amortized over 60 k pcs)
Total	—	US $1.03

9 Budget-Setting Checklist

Define Annual Volume & Life-of-Program Demand
Request Two Tooling Scenarios – aluminium bridge vs. steel, single vs. multi-cavity
Ask for a Cost Stack – separate lines for material, press, labor, overhead, scrap, tool amortization
Validate Cycle Time in T-1 – review cavity-pressure data to spot hidden seconds
Include Logistics – courier vs. ocean freight can swing landed cost by 10 %+

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Final Takeaway

Understanding each line in the injection-molding quote—tooling, material, press time, labor, and scrap—allows you to set realistic budgets, compare suppliers on equal footing, and make data-driven trade-offs between speed, cost, and quality.

Need a detailed cost breakdown? Upload your CAD to TaiwanMoldMaker.com and receive a no-obligation, 48-hour price calculation tailored to your project.