Slack's PMF score is 51%, measured by an independent study of 731 users answering the Sean Ellis question. That number has nothing to do with Glitch, the massively multiplayer game that Slack's team, then called Tiny Speck, spent years building before it failed. Nobody carried a score over. They built a completely different product and measured it from scratch.

That's the honest answer to "does my PMF score reset after a pivot?" Mostly, yes. But the more useful question is which part resets and which part doesn't, because conflating the two is where founders either panic over a number that was never real, or skip remeasuring when they should have.

The Glitch story, briefly

Tiny Speck built Glitch, a surreal, non-violent online game, and spent years on it. It didn't work, and they shut it down. But the team had also built an internal chat tool to coordinate their own work on the game, and by the time Glitch died, giving up that tool felt worse than giving up email would have. So they polished it, and in 2013 they released it as Slack (SitePoint, "Becoming Slack: The Story of a Son of a Glitch").

Whatever traction or lack of it Glitch had told the team nothing about whether Slack would work. It was a different product, solving a different job, for people who weren't even the same audience as game players. The chat tool had to earn its own fit, measured on its own terms, which is exactly what that later 51% score reflects.

A PMF score is a reading on a specific instrument pointed at a specific product. Change the product, and the old reading isn't wrong, it's just answering a question you're not asking anymore.

What resets

What doesn't reset

Measure the new thing on its own terms

PMFtracker runs the exact Sean Ellis question and scale, calculates your score automatically, and tracks it over time, so remeasuring after a pivot is a five-minute setup, not a research project.

Start Tracking PMF → Set up in 5 minutes · No credit card required

When to actually run the survey

Right after a pivot, you almost certainly don't have enough engaged users for a quantitative score to mean anything. Running a Sean Ellis survey on 8 early adopters produces a number with a margin of error wide enough to be meaningless. Two better moves for the gap between pivoting and having a real sample:

Once you're at roughly 40 engaged users on the new direction, run the real survey. Treat whatever number comes back as your actual starting point, not a comparison to whatever score the old product had.

The trap: comparing across products

The single most common mistake here isn't skipping the remeasurement, it's doing it and then treating the new number as a regression from the old one. A 22% score on a brand-new pivot compared against a 55% score on the abandoned product looks like backsliding. It isn't. It's two separate instrument readings on two separate products, and only one of them describes anything real right now. This is the same discipline behind avoiding a solution in search of a problem: judge the current product against current evidence, not against a story you're attached to.

The score resets because it has to, it was never measuring the pivot decision itself, only the product on the other side of it. What doesn't reset is the willingness to ask the question again, honestly, on a real sample, instead of assuming the old answer still applies.