This can easily get deep, but I’m going to tell you in the simplest way possible…
1. People actually use your product (!)
Captain Obvious, I know. According to Andrew Chen, PMF looks like DAU/MAU at over 25%; a world-class DAU/MAU would be over 50%. Apparently, it was a metric popularized by Facebook to gauge user retention.
That said, take the DAU/MAU metric with a grain of salt. There may be more nuances to this than meets the eye.
On the flip side, sometimes it will feel like pulling teeth to get someone to use your product.
That should be a red flag — either there’s no product-market fit, or you’re not reaching the right target audience.
2. People are very disappointed when they can no longer use your product
The original question is “40% of people would be very disappointed if they could no longer use the product,” which is what Sean Ellis used to see if Dropbox had product-market fit.
I think this is still a valid question to ask, but humans are quite bad at predicting future behavior. Hence, the revision.
This isn’t exactly something you would want to test on purpose, but if your product goes down and people are throwing a fit, you can be reasonably certain that your product was important to them.
3. People will go to great lengths to give you feedback, write you “thank you” notes, and/or complain about your product
If a product has potential, it will be evident by the number of people bothering you about it… even when the product has been ignored or otherwise put on the back burner.
We’ve had quite a number of inquiries on JLRPG, our Japanese language learning app. Because we’re scrappy, we built it fast… and unfortunately, it had some bugs. And goodness, did we hear about it. 😬
So, to illustrate…
Product with no fit:
Product with potential:
“I love this app! I recommend it to all my friends”
“This doesn’t work the way I want it to”
“Can you update the app with this feature I want?”
“Where do I find this thing I’m looking for?”
“Can you fix the damn app???”
Also this one… (oh my god they noticed it wasn’t getting updates 😅)
People haranguing you about a product means that they expected something, got a taste of their desired outcome, and felt that, by bothering you to update the product, they’ll get closer to that outcome.
Unless people are just angrily asking for refunds (another problem entirely), this is a good indicator of interest.
Conclusion: do people interact with your product of their own accord?
I believe there’s something similar between romance and products. When someone feels either love or hatred, they’re engaged in some way or another. But when they’re not even trying to make conversation, you know the spark is gone.
If you feel like people are giving you the polite “maybe,” I see that as a red flag. Consider what pain point you’re going after, and evaluate if it’s a real pain. Talk to people; don’t imagine it. That’s the only way you’ll know for sure.