If you’re building a consumer hardware product, there’s a moment early on where everything feels exciting – but also slightly chaotic. You’ve got a vision, a prototype forming in your mind (or on your desk), and potentially a team sprinting in multiple directions. At founder speed, it’s incredibly easy for misalignment, assumptions, and unnecessary rework to creep in.
A clear, lightweight Product Requirements Document (PRD) is one of the simplest tools you can use to protect your runway and keep everyone – from engineers to suppliers to investors – aligned on what you’re building and why.
This isn’t a corporate 80-page PDF. It’s a founder’s tool for clarity, speed, and better decision-making.
Here’s how to write one that actually gets used.
1. Start With a Clear Top-Line Summary
Begin your PRD with a concise, high-level explanation of what your product aims to achieve. This shouldn’t be a technical breakdown – it’s your “north star” statement.
- What problem does your product solve?
- Who is it for?
- Why does it matter enough to exist?
- How will the customer’s life improve because of it?
A great top-line summary allows every contributor – engineering, design, marketing, supply chain – to understand the purpose behind the product before diving into the details.
2. Break the Product Into Its Functional Components
Consumer goods are rarely a single monolithic thing. They’re a system. Breaking the product into its functional parts prevents ambiguity and helps each team know their scope.
Common component categories include:
- Main Chassis / Core Hardware
Structural materials, form factor, ergonomics, durability expectations. - Consumables / Replaceable Elements
Filters, cartridges, single-use components, consumable materials – define specs, expected lifecycle, and replenishment strategy. - Accessories
Charging docks, cases, stands, attachments, optional add-ons. - Electronics & Firmware (if applicable)
Sensors, power system, communication modules, expected performance ranges.
By decomposing the product into logical building blocks, you create a roadmap your design and engineering teams can immediately act on.
3. Include Cybersecurity Requirements for Connected Devices
If your product uses Bluetooth, Wi-Fi, cloud connectivity, apps, or any form of digital communication, cybersecurity can’t be an afterthought.
Your PRD should define:
- Data that is collected, stored, or transmitted
- Required encryption standards
- Authentication methods
- Update/firmware patch strategy
- Compliance requirements
- Expected threat model or attack vectors
Including this early prevents costly redesigns, failed certifications, or customer-trust issues later.
4. Add Diagrams, Schematics, and Layouts
Visuals make complexity digestible. Your PRD should include placeholders for:
- Mechanical diagrams
- Electrical schematics
- System architecture
- User journey maps
- Exploded views
- Rough mockups
Even preliminary illustrations help align expectations long before final CAD or engineering drawings are ready.
5. Analyze Your Competition & Why They’re a Threat
A useful PRD doesn’t just describe what you’re building. It explains why it matters, especially in the competitive landscape.
Document:
- Direct competitors (similar products)
- Indirect competitors (alternative solutions to the same problem)
- Their strengths and weaknesses
- Why customers choose them today
- Gaps or pain points in current offerings
- What meaningful differentiation your product delivers
This context helps teams make smarter trade-offs and avoid reinventing what already exists.
6. Track Your Target Markets & Expected Volumes
Your design decisions (materials, manufacturing methods, certifications) are shaped by where and how much you plan to sell.
Include:
- Primary markets (regions/countries)
- Regulatory requirements per market (if known)
- Forecasted annual volumes
- Seasonality or launch timing assumptions
- Demographic or usage insights
This ensures sourcing, tooling, and supply-chain planning are aligned from day one.
7. Admin: Keep Your PRD Alive
A PRD isn’t a document you write once and file away. It’s a living contract between teams.
Revision control is your friend.
Use version numbers, dates, and change logs. Make sure everyone knows where the most recent version lives. Ideally using an online platform that not only tracks revisions but also is the single source of truth.
Review it regularly.
Set a recurring reminder to revisit the PRD and compare it against current project status. Features shift, insights evolve, and unknowns become known – your document should reflect that.
Keep referring back to it.
A PRD is only useful if it’s used. Bring it into team meetings, design reviews, and roadmap discussions.
The Foundation of Your Product KPIs
A strong PRD sets the stage for your product KPIs – metrics that will later define success. Everything from consumer satisfaction to cost targets to usage patterns can trace back to expectations laid out in the PRD.
Need a second pair of eyes?
Building the right product is as much about clarity as creativity. If you’re at the stage where structure would help you move faster and with more confidence, I’m always happy to have a conversation.
