PMF Signal Ladder
Do we have fit, or just friendly users? Fit shows up as five signals, in order: people use it, return to it, rely on it, refer others, and pay. Each rung needs evidence from real behaviour, and no single rung is fit on its own.
Five signals, climbed in order.
What each signal needs
Friendly users can fake the lower rungs without meaning to. Each rung asks for behaviour that politeness can't produce.
Use
They try it on real work, not in a demo you're running for them.
A real task done in the product, by the person who has the problem.
Return
They come back when the problem comes back, without a reminder from you. Returning only after a nudge is the most common false signal there is.
Repeat use that you didn't prompt, at the rhythm the problem happens.
Rely
Taking it away would hurt. Sean Ellis's survey asks exactly this: how would you feel if you could no longer use it? He suggests that when around 40% answer "very disappointed", fit may be close. We use it as one reading on this rung, never as the verdict.
Their work now runs through the product, and they say what they'd lose.
Refer
They bring someone else without being asked. A referral risks their reputation, which is why it counts.
New users who arrived through an existing one, unprompted.
Pay
They pay, and keep paying when the novelty has worn off. Paying on its own is a sale; paying on top of the four rungs below is fit.
Renewals from the people who also return, rely and refer.
otlo: paid, and not yet claiming fit.
Own venture otlo, community intelligence for the people who build communities.
The rung reached
otlo has customers paying real money. On its own, that proves willingness to pay.
Why it isn't fit yet
Pay sits at the top of the ladder because it only means fit on top of the rungs below it. A payment without return and reliance is a sale.
What we're reading
Whether builders come back for every gathering without a reminder, and whether their community's life now runs through otlo.
When we'll say it
Only once retention data supports it. Until then the venture page says "paying customers", not "product-market fit".
Where it goes wrong
- Misread
Reading fit from the top rung alone
Why Payment can come from a relationship, a discount or a sales push. Fit is payment from people who also return, rely and refer.
- Misread
Counting prompted returns
Why If the only reason they came back was your reminder, you measured your reminder.
- Misread
Borrowing a retention number
Why A benchmark from another market says little about yours. Where we use a number, we say whose it is; otherwise it's a judgement, explained.
Try it in the Lab: Spot the Stall: The leaky launch is a puzzle about a venture that mistakes sign-ups for fit.
In the Journal: PMF: do they keep using it? and How to evaluate a venture studio
Published 28 September 2026. A Graylemon adaptation, which uses Sean Ellis's product-market fit survey as one measure on the rely rung.