Understanding injection molding cost per part is essential for any product manager, procurement engineer or entrepreneur planning a custom plastic component. Pricing can range from $0.05 for high-volume consumer parts to $50+ for low-volume medical or automotive components. This guide breaks down every cost factor so you can estimate your project budget with confidence.
What Drives Injection Molding Cost Per Part?
The total cost of an injection molded part is not just the plastic material. It includes mold fabrication, machine time, labor, overhead and post-processing. Understanding each element helps you identify where to optimize.
1. Mold Cost (Tooling)
The mold is typically the largest upfront investment. Mold prices depend on:
- Cavity count: Single-cavity molds cost less but produce fewer parts per cycle. Multi-cavity molds (2, 4, 8 or 16 cavities) increase output but raise tooling cost proportionally.
- Steel grade: P20 steel suits prototyping and low volumes ($3,000–8,000). H13 or S136 hardened steel handles millions of cycles ($8,000–30,000+).
- Part complexity: Undercuts, threads, thin walls and tight tolerances require slides, lifters and precision machining, adding 20–60% to mold cost.
- Surface finish: SPI A-1 mirror finishes require hand polishing and add significant labor cost compared to standard SPI C-3 textured finishes.
| Mold Type | Cavities | Steel | Estimated Cost (USD) | Lifespan (shots) |
|---|---|---|---|---|
| Prototype (aluminum) | 1 | Al 7075 | $1,500–3,000 | 1,000–5,000 |
| Low-volume production | 1–2 | P20 | $3,000–8,000 | 100,000–300,000 |
| Medium-volume production | 2–4 | H13 | $8,000–18,000 | 500,000–1,000,000 |
| High-volume production | 4–8 | S136/H13 | $15,000–40,000 | 1,000,000+ |
2. Material Cost
Plastic resin is priced per kilogram and varies significantly by type:
| Material | Price per kg (USD) | Common Applications |
|---|---|---|
| Polypropylene (PP) | $1.20–1.80 | Packaging, household goods, automotive |
| High-Density Polyethylene (HDPE) | $1.10–1.60 | Pallets, containers, pipes |
| ABS | $1.80–2.50 | Consumer electronics, toys, appliances |
| Polycarbonate (PC) | $3.00–4.50 | Transparent parts, safety equipment |
| Nylon (PA6/PA66) | $2.50–4.00 | Gears, bearings, industrial components |
| Glass-filled nylon | $3.50–5.50 | Structural parts, high-temperature use |
| TPE/TPR (soft touch) | $2.80–4.50 | Grips, seals, overmolding |
Material cost per part = (part weight in grams × 1.05 sprue/runner allowance) × price per gram.
3. Machine Time and Hourly Rate
Injection molding machines are billed by the hour. Rates depend on machine tonnage and location:
| Machine Tonnage | Clamping Force | Typical Hourly Rate (China) | Typical Hourly Rate (US/EU) |
|---|---|---|---|
| 80–120T | Small parts (<100g) | $15–25 | $60–100 |
| 150–250T | Medium parts (100–500g) | $20–35 | $80–140 |
| 300–500T | Large parts (500g–2kg) | $30–50 | $120–200 |
| 800–2500T | Very large parts (>2kg) | $60–120 | $200–400 |
Cycle time includes injection, cooling, mold open, part ejection and mold close. Typical cycles range from 15 seconds for thin-wall packaging to 90+ seconds for thick-walled structural parts.
4. Labor and Overhead
Each machine requires an operator for material loading, quality checks and packaging. In China, operator wages add $3–6 per machine hour. Overhead includes:
- Factory rent and utilities
- Equipment maintenance and depreciation
- Quality inspection and testing
- Packaging and labeling
- Management and administrative costs
Overhead is typically allocated as 30–50% of direct labor and machine costs.
Cost Per Part Formula
To calculate injection molding cost per part for a production run:
Cost per Part = (Mold Cost ÷ Total Production Volume) + Material Cost per Part + (Machine Hourly Rate × Cycle Time in Hours ÷ Cavities) + Labor/Overhead per Part
Practical Example: Plastic Storage Box
Let us calculate the cost for a 500g HDPE storage container produced in China:
| Cost Element | Calculation | Per-Part Cost at 10,000 Units | Per-Part Cost at 100,000 Units |
|---|---|---|---|
| Mold (4-cavity H13) | $12,000 ÷ volume | $1.200 | $0.120 |
| Material (HDPE) | 525g × $0.0014/g | $0.735 | $0.735 |
| Machine time | $25/hr × 45s ÷ 4 | $0.078 | $0.078 |
| Labor + overhead | ~40% of machine | $0.031 | $0.031 |
| Total per part | $2.044 | $0.964 |
This example shows why injection molding becomes dramatically more cost-effective at higher volumes. At 10,000 units, mold amortization dominates. At 100,000 units, material becomes the primary cost driver.
How to Reduce Injection Molding Costs
Experienced buyers use these strategies to optimize pricing:
Design for Manufacturing (DFM)
Simplify part geometry to eliminate undercuts, reduce wall thickness variation and standardize draft angles. DFM reviews by your molder can reduce mold cost by 15–30%.
Material Substitution
Switching from polycarbonate to ABS or from glass-filled nylon to mineral-filled PP can cut material costs by 30–50% without sacrificing performance.
Family Molds
For multi-component products, a family mold produces several related parts in one shot. This reduces total mold investment by 20–40% compared to individual molds.
Offshore Manufacturing
China injection molding typically costs 40–60% less than US or European production for equivalent quality. Total savings include lower mold fabrication costs, machine rates and labor.
Hidden Costs to Watch
Beyond the obvious line items, budget for:
- Product development: 3D modeling, prototype printing and DFM analysis ($500–3,000)
- Mold modifications: Post-trial adjustments average $500–2,000 per engineering change
- Quality control: CMM inspection, material testing and dimensional reports ($200–1,000 per batch)
- Shipping and duties: Sea freight from China adds $0.02–0.08 per part depending on volume
- Inventory carrying cost: MOQ commitments may require holding 3–6 months of stock
When Does Injection Molding Make Sense?
Injection molding is most cost-effective for annual volumes above 5,000 units. Below this threshold, consider alternatives:
| Volume (Annual) | Recommended Process | Typical Cost Range |
|---|---|---|
| 1–100 units | 3D printing (FDM/SLA) | $5–50 per part |
| 100–1,000 units | Silicone molding / urethane casting | $3–15 per part |
| 1,000–5,000 units | Aluminum mold injection molding | $1–5 per part |
| 5,000–50,000 units | Steel mold, single-cavity | $0.50–3 per part |
| 50,000+ units | Steel mold, multi-cavity | $0.10–1 per part |
Getting an Accurate Quote
To receive a precise injection molding cost per part quotation, provide your supplier with:
- 3D CAD files (STEP or IGES format)
- Material specification or application requirements
- Annual volume forecast and first-order quantity
- Surface finish and tolerance requirements
- Color and branding specifications
- Quality standards (ISO, automotive, medical)
For buyers sourcing from China, our OEM buying guide explains how to evaluate mold shops, request samples and manage quality remotely.
Related reading: Injection Molding Quality Control: Inspection Guide.
Request a Custom Injection Molding Quote
FOSHAN LSY Plastic operates 180T–2500T JSW and Mitsubishi injection molding machines with in-house mold design and CNC workshop. We produce custom plastic parts for automotive, electronics, hotel supply and logistics clients including BYD, OPPO and vivo. Send your 3D files to fstyx01@lsyplastic.com or WhatsApp +86 19311059570 for a detailed cost breakdown and DFM review.