For development costs: If you are building an app, make a list of number of 1. Views. A complex UI can have multiple views. E.g. the menu at the top, the menu

For development costs: If you are building an app, make a list of number of 1. Views. A complex UI can have multiple views. E.g. the menu at the top, the menu on the side, the search box, the list of items shown are all different views which are integrated together. 2. Make a list of all data models. Each type of user, each type of item stored in its own table or collection is a different data model. 3. Multiply number of unique views by 3 and number of models by 10 and then add these numbers, to get total number of hours of development effort. 4. For each mobile OS and the web the views will be counted separately. 5. Multiple total number of hours by your hourly billing rate.