Product–Market Fit
Evaluates evidence of repeatable demand, retention, and willingness to pay for the product.
About this assessment
Product-Market Fit is the second stage of the ProductBooks evaluation framework. It determines whether your product generates repeatable demand, whether users retain without external prompting, and whether willingness to pay is demonstrated through actual behaviour rather than stated intent. Many teams assume product-market fit based on early adoption signals. This evaluator tests whether those signals hold up under evidence-based scrutiny.
Evaluators apply strict evidence definitions.
Evidence that does not meet the definitions scores zero.
Typical flow
- 1Evaluate
- 2Identify missing evidence
- 3Generate evidence via operators
- 4Re-evaluate
Optional overview (3 min)
When to use this assessment
Use the Product-Market Fit evaluator when you have an active product with users, but need to determine whether the adoption and retention signals you are seeing represent genuine product-market fit or are artifacts of launch momentum, incentives, or founder-driven sales.
- Users exist but retention and engagement are unclear or declining
- You are considering scaling spend or team size based on adoption signals
- You need to distinguish real demand from launch-driven or incentive-driven activity
Evaluation scope
Decides
Whether users return without external prompting
Does not do
Validate growth tactics
Decides
Whether demand exists beyond early adopters
Does not do
Predict market size
Decides
Whether willingness to pay is demonstrated, not assumed
Does not do
Help you "pass"
| This evaluator decides | This evaluator does not do |
|---|---|
| Whether users return without external prompting | Validate growth tactics |
| Whether demand exists beyond early adopters | Predict market size |
| Whether willingness to pay is demonstrated, not assumed | Help you "pass" |
Evidence requirements
- Retention must be organic, not incentivised
- Demand signals must be repeatable
- Payment behaviour outweighs stated intent
- Missing evidence scores zero
How missing evidence is generated
If required evidence is missing, ProductBooks uses controlled operators to generate it.
Operators generate evidence. They do not decide fit.
Demand Reality Operator
Generates scoreable acquisition evidence by observing whether new users arrive through repeatable channels without outreach, campaigns, or launch-driven effort.
Run operatorPayment Conversion Operator
Generates scoreable monetization evidence by observing whether users accept or reject a fixed paid offer without negotiation, discounts, or persuasion.
Run operatorRetention Without Reminders Operator
Generates scoreable retention evidence by observing whether users continue engagement or payment without reminders, nudges, or follow-ups.
Run operatorReplacement Behaviour Operator
Generates scoreable replacement evidence by observing whether users fully replace an existing solution or workflow instead of running products in parallel.
Run operatorOrganic Pull Operator
Generates scoreable advocacy evidence by observing whether users create demand through unsolicited referrals or recommendations without prompts or incentives.
Run operatorInterpreting your results
A high Product-Market Fit score means you have demonstrated, through verifiable evidence, that users return without prompting, that demand exists beyond early adopters, and that willingness to pay is demonstrated through actual behaviour. A low score indicates that one or more of these conditions has not been evidenced to the required standard.
The evaluator will identify specific gaps in your retention, demand, or monetisation evidence. Use the operators above to generate the missing evidence through structured user observation, then re-run the evaluator.
Related assessments
Product-Market Fit is preceded by Problem-Solution Fit, which validates that the underlying problem and solution are real. If you have not yet completed this stage, it is recommended before proceeding.
The next stage in the cascade is Business Model Fit, which evaluates whether your business model can sustainably support the product and market you serve.
Learn more about why products fail before achieving real market fit in our article on why products fail before market fit.
Evaluator contract: This evaluator applies definitions strictly. Disputes do not change scoring.