Metrics can be misleading. The founder's true "aha" moment for product-market fit came from solving a complex, real-world problem posed by a skeptical expert during a live demo. When the product solved in seconds what took the customer's team two weeks, it provided undeniable proof of value in a high-stakes environment.

Product-market fit isn't a sudden switch but a palpable shift in momentum. As a founder, you feel the change from pushing against the current (hard selling with little traction) to suddenly being pulled by it (easier sales, inbound interest). This directional change in velocity is the clearest signal that you're onto something.

Product-market fit isn't just growth; it's an extreme market pull where customers buy your product despite its imperfections. The ultimate signal is when deals close quickly and repeatedly, with users happily ignoring missing features because the core value proposition is so urgent and compelling.

For Ethic, the feeling of true product-market fit wasn't just hitting metrics, but the moment they helped an advisor win a major new client. The founder realized this success was a replicable playbook that could be repeated, creating a flywheel for growth. The metrics then followed this initial breakthrough.

Initially, customers often "round down," focusing on missing features. A key sign of product-market fit is when they start "rounding up"—their faces light up in demos, and they imagine the product's future potential, forgiving current limitations because they believe in the core value.

You've achieved product-market fit when the market pulls you forward, characterized by growth driven entirely by organic referrals. If your customers are so passionate that they do the selling for you, you've moved beyond just a good idea.

Technical founders often create a perfect solution to a real problem but still fail. That's because problem-solution fit is useless without product-market fit. An elegant solution that isn't plugged into the market—with the right GTM, pricing, and messaging—solves nothing in practice. It's unheard and unseen.

Sales are a vanity metric for product-market fit. The real test is having ~25 customers who have successfully implemented your product and achieved the specific ROI promised during the sales process. If you don't have this, you have a product problem, not a go-to-market problem.

When testing new ideas, the right one will provide clear and immediate positive feedback. Tempur-Pedic knew pillows were a winner when 25% of chiropractors in a test mailing immediately placed an order. This strong, early signal indicated product-market fit, unlike other failed tests.