Every stuck marketplace we are brought in to diagnose has a dashboard, and the dashboard is almost always tracking the wrong things. Total signups. App downloads. Listings created. Numbers that only go up, feel like progress, and predict nothing about whether the platform will exist in two years. This post is the KPI set we actually use, what each number tells you, and, because the honest answer depends on stage, which single number deserves your attention right now.
A note on jargon: every metric below is defined in plain language here, and in more depth in our marketplace glossary. If a term is new, it is explained, because a KPI you cannot explain to your team is a KPI you cannot act on.
Vanity Metrics vs Vital Signs
The test for whether a metric matters is simple: does it measure the exchange? A marketplace exists to make transactions happen between two sides. Any number that can grow while transactions stall is decoration. Signups can grow while nobody transacts. Listings can grow while every search fails. Even revenue can grow, briefly, while the cohorts underneath it rot.
The metrics that matter cluster into four families: liquidity, economics, retention, and supply health. You need a view of all four, but not with equal urgency at every stage.
Liquidity: The KPIs That Come First
Liquidity is the likelihood that a participant finds what they came for within a reasonable time. It is the single truest health metric of a marketplace, and it is measured, not felt.
Search-to-fill rate:the share of searches that end in a completed transaction. This is the demand side’s experience of your platform expressed as one number. A falling search-to-fill rate is the earliest warning you will get that supply, matching, or pricing is off.
Fill rate: the share of requests that get fulfilled, such as booking requests accepted or jobs completed. Low fill rates burn demand-side trust fast, because a user whose request goes nowhere rarely tries twice.
Time to fill: how long a match takes. Every category has a tolerance window, and exceeding it is functionally the same as failing.
Utilization:how much of the available supply actually gets used. Low utilization is the supply side’s version of a failed search, and it predicts supplier churn before churn shows up anywhere else.
Economics: GMV, Take Rate, and What Investors Read
GMV, gross merchandise value, is the total value of everything transacted through the platform in a period. It measures scale, not health. A marketplace can grow GMV while losing money on every transaction, which is why GMV belongs on the dashboard but never alone.
Net revenue is what you actually earn: GMV times take rate, plus any subscription or listing fees. Investors read net revenue and its growth rate far more seriously than GMV, and so should you.
Contribution margin per transaction is the profit and loss of a single exchange, fully loaded: your fee, minus payment processing, support cost, and incentives. If this number is negative, growth makes the problem bigger. The take rate that drives it is a strategy decision in its own right, which we covered in take-rate is not a number.
CAC by side: what it costs to acquire one supplier and, separately, one buyer. Marketplaces have two acquisition costs, they are rarely equal, and knowing which side is cheaper shapes the whole growth plan.
Retention: The Metrics That Predict Survival
Second-transaction rate is the share of users who come back and transact again. We have made the full argument in second transaction beats first: first-transaction conversion is a vanity metric by comparison, because the second transaction is the one that predicts whether the marketplace will still exist in twelve months.
Cohort retention curves group users by the month they joined and track each group over time. Cohorts reveal what averages hide: whether newer users retain better than older ones, which is the only trustworthy evidence that the product is improving.
If you can only watch one number after liquidity is real, watch second-transaction rate, weekly, split by side. Everything else is commentary.The dashboard rule we give every client
Supply-Side Health, Measured Separately
Supply-side churn is the silent killer of marketplaces that have already found fit: when good providers leave, selection degrades, demand follows, and the loop runs in reverse. Because supply decay hides inside healthy-looking totals, it needs its own panel: active supplier rate (listed and available, not just registered), supplier churn by cohort, time to first transaction for new suppliers, and the share of new suppliers who reach that first transaction within thirty days.
That last one deserves special attention. Suppliers who transact in their first thirty days retain at dramatically higher rates, which is why hand-onboarding early supply pays off long after the effort stops feeling scalable.
The One Number That Matters, by Stage
| Stage | The number | Why it rules this stage |
|---|---|---|
| Pre-launch | Manual transactions closed | Evidence both sides want the exchange; everything else is projection |
| Cold start | Search-to-fill rate in your wedge | Proves liquidity exists somewhere before you spend on growth |
| Early traction | Second-transaction rate | Predicts whether acquisition spend compounds or leaks |
| Growth | Contribution margin per transaction | Determines whether scale helps you or bleeds you |
| Scale | Cohort LTV to CAC, by side | The whole machine, expressed as one ratio |
What Changes for B2B Marketplaces
B2B marketplace KPIs follow the same logic with three adjustments. Frequency is lower and order values are higher, so quote-to-order rate and reorder rate replace search-to-fill as the liquidity workhorses. Accounts matter more than users, so retention is measured on organizations, and a single logo can move a cohort. And payment terms create a working-capital metric consumer platforms never think about: days between paying out suppliers and collecting from buyers. If you are building in that category, our B2B and procurement marketplace overview covers how the model differs end to end.
Instrumenting these numbers, and knowing which one your next decision hangs on, is standard work inside our growth engagements and marketplace consulting. If your dashboard is full and your confidence is low, that is usually a measurement problem, and it is fixable in weeks.
