Ask current customers how they would feel if they were unable to utilise your product: Very dissatisfied, a little dissatisfied, or not dissatisfied. At least 40% of users must say they would be “extremely disappointed” without your product for there to be a product/market fit. Focus intensely on achieving product/market fit when you are under 40% because it is too early to start growth hacking.
Source www.startup-marketing.com