If you're building a product, you've heard the term "product-market fit." But what does it actually mean — and how do you know when you have it?

The Problem with Gut Feel

Most founders rely on intuition: "Users seem happy." "Growth is steady." "Nobody's churning... much." These are signals, but they're not measurement. You can convince yourself you have PMF when you're riding early-adopter enthusiasm that won't last.

The Superhuman Method

In 2018, Rahul Vohra (CEO of Superhuman) published a framework that changed how startups think about PMF. The core question:

"How would you feel if you could no longer use [product]?"

Respondents choose: Very disappointed, Somewhat disappointed, or Not disappointed.

The benchmark: if 40% or more say "very disappointed," you have product-market fit. Below that, you don't — yet.

Why 40%?

Vohra analyzed hundreds of startups and found that the 40% threshold consistently separated companies that went on to scale from those that stalled. It's not a magic number — it's an empirically validated benchmark.

Beyond the Single Number

The real power isn't in the headline percentage. It's in what you do with the segments:

"Very disappointed" users are your core. Study them. What do they have in common? That's your ideal customer profile.
"Somewhat disappointed" users are your opportunity. They see value but something's missing. Their feedback is your product roadmap.
"Not disappointed" users are noise for now. Don't optimize for them — you'll dilute your product.

Measuring Over Time

PMF isn't a one-time event. It's a signal you track continuously. Run the survey after meaningful usage (not on day one), segment by cohort, and watch the trend. A product can have PMF, lose it after a bad release, and earn it back.

Getting Started

The simplest way to start: send the survey to 30+ active users who've had enough time to form an opinion. Segment the results by user type. Act on the "somewhat disappointed" feedback first — that's where the leverage is.

Product-market fit isn't a destination. It's a practice.