Calm is not an MVP. It’s a full-featured app with a lot of content and features. The app has audio and video, as well as a variety of meditations and sleep stories.To build an app like Calm, we can roughly predict that it will take 6 months to one year. For new products, we recommend creating an MVP with the most important features and the unique value proposition by consulting a custom iPhone app development company. They can test your app with real users, and if you’re successful, it may also begin to bring you ROI.