How to Write a Product Specification Sheet
A specification is the only document that defines what you are buying. Without one, you are buying whatever arrives. Parameters with limits and methods, plus the sections most brand owners omit: sensory, packaging and shelf life.
Why You Need One
This guide is for brand owners in India commissioning manufactured products.
Without a written specification, there is no agreed definition of a conforming product. A batch that tastes different, looks different or tests differently from the last one cannot be rejected, because nothing states what it should have been.
The specification is also what makes a certificate of analysis meaningful. A certificate reports results against limits, and the limits come from the specification. No specification, no basis for judging the results.
And it is what makes a manufacturer change portable. If you later move production, the specification is what the new manufacturer works to, which is why holding your own signed specification matters more than most brand owners realise at the outset.
The Structure
Sections every specification should have.
| Section | What It Contains |
|---|---|
| Product identity | Name, code, dosage form and strength or grade |
| Composition | Each ingredient with its quantity and its own specification reference |
| Appearance | Described precisely, not as “normal” |
| Sensory parameters | Taste, odour, texture, with an approved reference sample |
| Physical parameters | Weight, dimensions, pH, viscosity, as applicable to the form |
| Identification tests | For the actives, with methods |
| Assay | Active content with a limit range and a named method |
| Microbial limits | Total counts and specified pathogens |
| Heavy metals | Each metal with a maximum |
| Contaminant tests | Residual solvents, pesticides, aflatoxins as applicable |
| Performance tests | Disintegration, dissolution, dispersibility, as the form requires |
| Packaging specification | Each component with its own detail |
| Labelling reference | Approved artwork version number |
| Shelf life and storage | With the conditions stated |
| Documentation per batch | What the manufacturer supplies with each delivery |
| Version control | Version number, date and signatures of both parties |
Composition should reference each ingredient’s own specification rather than just naming it. “Ashwagandha extract” is not a specification; “Ashwagandha root extract, 2.5 percent withanolides by HPLC, per attached raw material specification” is.
Writing Limits Properly
This is where specifications succeed or fail.
Every Parameter Needs a Limit
A number or a range, not a target. “Approximately 500mg” cannot be judged; “495 to 505mg” can.
Every Limit Needs a Method
Named specifically. The same parameter measured by different methods can give different figures, both correct.
Decide Which Way the Limit Runs
Maximum, minimum or a range. Each parameter needs this stated explicitly.
Make Limits Achievable
A limit tighter than the process can reliably hold produces constant failures and pressure to ignore the specification, which is worse than a realistic limit.
Discuss achievability with your manufacturer before finalising. A specification written without that conversation often contains at least one limit that cannot be met consistently, and the result is a specification nobody treats as binding.
The Sections Usually Left Out
These cause most real disputes.
Sensory parameters are the biggest omission. Taste, odour and texture are what consumers notice and complain about, and they are almost never specified. Specify them by reference to a physically approved and retained sample, and state who holds that sample and for how long.
Packaging specification is the second. Each component needs its own detail: bottle material and weight, cap type and liner, induction seal presence, carton board specification, label material and adhesive. “Standard HDPE bottle” is not a specification, and packaging substitutions are a common source of unexpected quality changes.
Shelf life with storage conditions is the third. A shelf life stated without conditions is unenforceable, because the product’s behaviour depends on how it was stored.
And the documentation list: exactly which documents accompany each batch. Without it, documentation becomes a request each time rather than an obligation.
Version Control
Simple, and routinely neglected.
- Give every specification a version number and a date.
- Have both parties sign each version.
- Keep every superseded version, since batches were made to them.
- Record which version each batch was manufactured against.
- Agree that changes require written agreement from both sides.
- Agree a notification obligation if the manufacturer needs to change anything.
- Review the specification periodically rather than only when something fails.
- Keep the approved reference sample aligned with the current version.
Checklist
Before signing a specification.
- State product identity, dosage form and strength or grade.
- List composition with each ingredient’s own specification referenced.
- Describe appearance precisely rather than as normal.
- Specify taste, odour and texture against a retained approved sample.
- State who holds the reference sample and for how long.
- Specify physical parameters relevant to the dosage form.
- Include identification and assay with limits and named methods.
- Include microbial limits with specified pathogens.
- Include heavy metal maximums.
- Include contaminant tests applicable to your materials.
- Include performance tests the dosage form requires.
- Specify each packaging component in detail.
- Reference the approved artwork version.
- State shelf life with storage conditions.
- List the documents supplied with each batch.
- Confirm every limit has a direction and a method.
- Discuss achievability of each limit with the manufacturer.
- Version, date and have both parties sign it.
- Keep your own signed copy independently of the manufacturer.
Need Help Writing a Specification?
Share your product and our team will set out the parameters, methods and documentation we would work to.
Frequently Asked Questions
Why does a written specification matter?
Because without one there is no agreed definition of a conforming product, so a batch that tastes, looks or tests differently cannot be rejected. It is also what makes a certificate of analysis meaningful, since the limits come from the specification.
What is the test of a good specification?
Whether a different competent manufacturer, given that document alone, could make a product you would accept. That also makes the specification what lets you move production later.
Which section is most often left out?
Sensory parameters. Taste, odour and texture are what consumers notice and complain about, and they are almost never specified. Specify them against a physically approved and retained sample, and state who holds it.
How should limits be written?
Every parameter needs a number or range rather than a target, with the direction stated as maximum, minimum or range, and a named method. Discuss achievability with the manufacturer first, since an unachievable limit produces a specification nobody treats as binding.
What about packaging?
Specify each component in detail: bottle material and weight, cap type and liner, induction seal, carton board, label material and adhesive. “Standard HDPE bottle” is not a specification, and packaging substitutions are a common source of unexpected quality changes.