When you outsource multi-component assembly, pricing isn't a simple unit cost—it's a layered calculation that includes materials, labor, setup, tooling, and overhead. Understanding how contract manufacturers break down these costs will help you negotiate smarter and avoid surprise invoices mid-production.
How Contract Manufacturers Calculate Assembly Costs
Most contract assembly shops price work in one of three ways: per-unit pricing, cost-plus markup, or project-based quotes. Per-unit pricing works well for high-volume runs (5,000+ units) where setup costs are spread thin. Cost-plus arrangements are common for mid-volume work (500–5,000 units) and typically add 15–35% overhead to direct costs. Project-based pricing suits one-offs or small batches where the manufacturer quotes the entire job upfront, including all labor and materials.
The devil lives in the details. A $2 assembly might involve $0.80 in component costs, $0.50 in direct labor (30 seconds of technician time), $0.40 in overhead allocation, and $0.30 in profit margin. Change one variable—swap a connector for a more expensive one, add a custom label, or request tighter tolerances—and that unit cost shifts instantly.
Breaking Down the Major Cost Drivers
Material sourcing accounts for 40–60% of total assembly cost on average. Your manufacturer can either supply components (markup: 8–15%) or work with your bill of materials (BOM). Providing your own parts saves money but requires inventory management and sometimes minimum order quantities that don't align with your production schedule.
Setup and tooling are fixed costs that get amortized across your run. A custom jig or fixture might cost $500–$2,500, but on a 10,000-unit order, that's $0.05–$0.25 per unit. On a 100-unit order, it's $5–$25 per unit. This is why minimum order quantities exist.
Labor complexity varies enormously. Hand-soldering a control board takes longer than snapping together plastic enclosures. Expect to pay $15–$35 per labor hour at contract shops in North America; offshore manufacturers may charge $5–$12 per hour but often require larger minimums and longer lead times (8–12 weeks vs. 2–4 weeks domestically).
Quality and testing add 10–25% to costs if you require:
- In-circuit testing (ICT)
- Functional testing
- Traceability documentation
- Certification prep (CE, FCC, UL)
Budget-conscious manufacturers often skip testing, then deal with field failures—a costly mistake with medical, automotive, or safety-critical products.
What to Request in a Quote
When approaching a contract manufacturer, provide:
- Detailed BOM with part numbers, quantities per unit, and preferred suppliers
- Assembly sequence or technical drawings highlighting tricky steps
- Expected annual volume and initial production run size
- Quality standards and test requirements
- Timeline constraints
Ask for quotes broken into line items: material costs, labor per unit, setup fees, tooling costs, and testing. Transparency here lets you spot where to negotiate. If someone quotes $5 per unit with no breakdown, they're hiding margin or cutting corners—probably both.
Volume Discounts and Minimum Orders
Most contract manufacturers offer tiered pricing. A typical structure:
| Volume | Cost Per Unit | |--------|---------------| | 100–500 | $4.50 | | 501–2,000 | $3.80 | | 2,001–10,000 | $3.10 | | 10,001+ | $2.40 |
The jump between tiers reflects reduced per-unit overhead and negotiating power with suppliers. However, larger minimums mean cash tied up in inventory. Factor in your actual market demand—ordering 10,000 units to save $1.10 per unit is only smart if you'll sell them.
Hidden Costs to Watch For
NRE (non-recurring engineering) charges run $500–$5,000+ for design optimization, fixturing, and process documentation. Some manufacturers bundle this into the first order; others bill separately.
Packaging and shipping can add 15–30% to the final cost, especially for fragile assemblies or international delivery.
Lead time premiums apply when you need expedited scheduling. A 4-week order might cost 10–20% more if you compress it to 2 weeks.
Change orders during production are expensive. A design revision mid-run can cost 25–50% of the original setup fee.
Finding Competitive Quotes
Don't settle for the first offer. Request quotes from at least 3–5 qualified manufacturers. Check certifications (ISO 9001, IPC-A-610 for electronics), ask for references on similar products, and visit the facility if possible. Mercoly helps you compare and find trusted contract assembly providers in one place, streamlining this research.
Frequently Asked Questions
Q: How much does setup typically cost for a small batch (100–500 units)? Setup fees for simple assemblies range $300–$1,500, depending on the jig complexity and labor involved. For electronics or precision work, budget $1,000–$3,000.
Q: Should I provide components or let the manufacturer source them? If you have a stable supply and favorable pricing, source yourself and save 8–15%. If you're uncertain about volumes or supplier relationships, let the manufacturer source—the overhead is worth the simplicity and liability shift.
Q: What's a realistic timeline for contract assembly? Domestic: 2–4 weeks for standard runs. Offshore: 6–12 weeks plus shipping. Expedited runs cost 20–50% premium and might arrive in 1–2 weeks.
Reach out to manufacturers with your BOM and realistic volume projections, and you'll get actionable quotes fast.