Wearable Bill of Materials: Where Unit Cost Really Goes
A wearable bill of materials is rarely dominated by the component a buyer expects. In most projects the silicon is a modest share, while tooling amortisation, the display stack, sensor count, packaging structure and the certification scope booked per hardware revision decide whether the landed cost works. This article sets out the cost drivers we see in quotation reviews, without quoting prices, so a category buyer can interrogate a supplier's BOM line by line. It applies to glasses, rings, education devices and companion models alike.
Tooling is a fixed cost spread over a volume you have not sold yet
Injection tooling, jigs, test fixtures and the first-article process are paid once and recovered across the order. That is why the same design quoted at 500 units and at 5,000 units produces two different unit costs, and why a supplier's headline figure is meaningless without the volume assumption attached to it. Ask whether tooling is charged as a one-off, amortised into the unit price, or partly both, and who owns the tool if the relationship ends. Our OEM/ODM services page sets out how tooling and NRE are separated on a quotation, and the OEM versus ODM note explains which route carries which fixed cost.
The display and enclosure set the floor
A transflective or low-power display, a bonded cover glass and an IP-rated enclosure are the three items that most often move a wearable BOM. Each adds a process step, a yield risk and a test requirement. A sealed enclosure needs an ingress test station; a bonded display needs a lamination yield assumption. Buyers should ask for the BOM split by sub-assembly rather than a single unit figure, then ask which lines are volume-sensitive and which are fixed. If a supplier cannot break the BOM down, that is a signal about how the factory is managed.
Sensors, radios and the compliance they trigger
Every added radio or sensor changes the certification file. A wearable with Bluetooth alone sits in a narrower test scope than one with Wi-Fi, cellular or a laser ranging module. Under our published policy, CE RED scope covers EN 300 328, EN 301 489 and EN 62368-1, with FCC Part 15 B/C, UKCA on request, RoHS 3, REACH SVHC screening, battery UN38.3 plus SDS, and EN 1811 nickel release for skin-contact items. Toy scope (EN 71-1/-2/-3, EN 62115, Toy Safety Directive 2009/48/EC) is decided by the age grading printed on the packaging and booked with an accredited laboratory per build. We do not hold certificates in advance: the test scope is booked per hardware revision, so a sensor change late in the project means a new booking and a new schedule.
| BOM area | What drives the cost | What to ask the supplier |
|---|---|---|
| Tooling and fixtures | Number of tools, mould complexity, test jigs | One-off, amortised, or both; who owns the tool |
| Display and cover glass | Technology, bonding process, lamination yield | Yield assumption and rework path |
| Sensors and radios | Count, interface, calibration steps | Which lines trigger new certification scope |
| Battery and charging | Cell format, protection board, UN38.3 file | Who maintains the SDS and transport documents |
| Packaging | Structure, print process, retail or bulk | MOQ for custom packaging and artwork rounds |
| Certification | Test scope per hardware revision | Which markets, which standards, booked with whom |
| Assembly and QC | Test gates, AQL level, rework rate | IQC/IPQC/FQC/OQC coverage at AQL 2.5/4.0 |
Module versus custom build: the volume threshold
A module build reuses an existing enclosure, board and firmware base, so tooling is small and the certification file already exists for that hardware revision. A custom build buys differentiation at the price of tooling lead time, which runs 12-20 weeks for ODM tooling, and a fresh compliance file. The decision is not about ambition; it is about whether your forecast can absorb the fixed cost. Compare the two against your realistic first-year volume, not your best case.
- MOQ standard 500 units; logo 500; custom packaging 1,000; firmware or app white-label 2,000.
- AI glasses 300 units; ring, education and companion models 1,000 units; service robots quoted per project at 50 units.
- Samples: stock 3-5 days, configured 7-15 days, cost credited against mass production.
- Production 25-35 days, education 30-40 days, ODM tooling 12-20 weeks; EXW, FOB Shenzhen, DDP air or sea.
- Warranty 12 months with 2 per cent free replacement parts shipped with the order.
Where the importer carries the cost, not the factory
Packaging and compliance are the two lines buyers most often forget to cost. A retail box needs artwork rounds, a print process and a structure that survives transit; a bulk pack does not. On the regulatory side, EU and UK importer duties under WEEE, BattG, DEEE/Triman and EORI/VAT registration sit with the importer, not with us. Google Play and GMS are not licensed by default, so any app-store dependency must be priced into your launch plan. Health metrics on a companion or ring product are wellness guidance, never diagnosis, and a companion robot is not a monitoring or emergency-response device. Those boundaries shape what you may claim in retail copy, and therefore what the packaging must say. Before you approve a BOM, walk the supplier vetting checklist and confirm the QC gates and test process behind the quoted assembly cost.
The practical next step is a line-by-line BOM review against your own forecast: fixed versus volume-sensitive lines, certification scope per revision, packaging MOQ and importer duties. Send the specification and target volume through our contact page, and we will return a split quotation rather than a single unit figure. Buyers who want the wider category context can start from the product catalogue and the journal.
Questions buyers ask
Why does the same wearable design cost differently between two suppliers?
The gap is usually not the main chip but the surrounding decisions: tooling amortisation, display choice, sensor count, packaging structure and how much certification scope is booked per hardware revision. Ask for the BOM split by sub-assembly rather than a single unit figure.
Should we start with a module build or a fully custom wearable?
A module build reuses an existing enclosure and board, so tooling and certification scope are smaller and the first shipment arrives sooner. A custom build buys you differentiation but adds tooling lead time and a new compliance file for every revision.
Related: more on ai smart hardware · buyer guides · customisation tiers