Product/Market Fit
Product/market fit, also known as product-market fit, is the degree to which a product satisfies a strong market demand. Product/market fit has been identified as a first step to building a successful venture in which the company meets early adopters, gathers feedback and gauges interest in its product.
The 40% rule. One metric for product/market fit is if at least 40% percent of surveyed customers indicate that they would be “very disappointed” if they no longer have access to a particular product or service.