How Superhuman Built an Engine to Find Product-Market Fit

Y Combinator founder Paul Graham described product-market fit as when you've [made something that people want](http://www.paulgraham.com/13sentences.html?ref=blog.superhuman.com), while Sam Altman [characterized](http://blog.samaltman.com/before-growth?ref=blog.superhuman.com) it as when users spontaneously tell other people to use your product.)

[Sean Ellis](https://www.linkedin.com/in/seanellis?ref=blog.superhuman.com), who ran growth in the early days of [Dropbox](https://www.dropbox.com/?ref=blog.superhuman.com), [LogMeIn](https://www.logmein.com/?ref=blog.superhuman.com), and [Eventbrite](https://www.eventbrite.com/?ref=blog.superhuman.com) and later coined the term "growth hacker".)

Ellis had [found](http://www.startup-marketing.com/the-startup-pyramid/?ref=blog.superhuman.com) a *leading* indicator: **just ask users "how would you feel if you could no longer use the product?" and measure the percentage who answer "very disappointed".**)

After benchmarking nearly 100 startups with his [customer development survey](https://pmfsurvey.com/?ref=blog.superhuman.com), Ellis found that the magic number was 40%. Companies that struggled to find growth almost always had less than 40% of users respond "very disappointed", whereas companies with strong traction almost always exceeded that threshold.)

A helpful example comes from [Hiten Shah](https://firstround.com/review/advice-is-cheap-context-is-priceless/?ref=blog.superhuman.com), who posed Ellis' question to [731 Slack users](https://hitenism.com/slack-product-market-fit-survey/?ref=blog.superhuman.com) in a 2015 open research project. 51% of these users responded that they would be very disappointed without Slack, revealing that the product had indeed reached product-market fit when it had around half a million paying users. Today, this isn’t too surprising, given Slack's legendary [success story](https://blog.superhuman.com/how-to-tell-a-billion-dollar-story/). Truly, this example shows just how *hard* it is to beat the 40% benchmark.)

With your early marketing, you may have attracted all kinds of users — especially if you've had press and your product is free in some way. But many of those people won't be well-qualified; they don't have a real need for your product, and its main benefit or use case might not be a great fit. You wouldn't have wanted these folks as users anyway.)

I turned to [Julie Supan](https://www.linkedin.com/in/juliesupan/?ref=blog.superhuman.com)'s [high-expectation customer framework](https://firstround.com/review/what-i-learned-from-developing-branding-for-airbnb-dropbox-and-thumbtack/?ref=blog.superhuman.com) as a tool to do just that. Supan notes that the high-expectation customer (HXC) isn't an all encompassing persona, but rather the most discerning person within your target demographic. Most importantly, they will enjoy your product for its greatest benefit and help spread the word. For example, Airbnb's HXC doesn’t simply want to visit new places, but wants to belong. For Dropbox, the HXC wants to stay organized, simplify their life, and keep their life's work safe.)

These [words of wisdom from Paul Graham](http://paulgraham.com/startupideas.html?ref=blog.superhuman.com) explain why:

This batch of not disappointed users should not impact your product strategy in any way. They'll request distracting features, present ill-fitting use cases and probably be very vocal, all before they churn out and leave you with a mangled, muddled roadmap. As surprising or painful as it may seem, don't act on their feedback — it will lead you astray on your quest for product-market fit.)

However, this shouldn't cause too much anxiety, as there are some ways around it. If your business has strong network effects (think Uber or Airbnb), then the core benefit will keep getting better as you grow. If you're a SaaS company like Superhuman, you simply have to keep on improving the product as the pool of users expands. To do that, we rebuild our roadmap every quarter using this process, ensuring that we're improving our product-market fit score fast enough.)