How to build a cost calculator app?

Robert - ruby-on-rails
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As an example I use this:

What do I want to have?

  • nice & simple mobile first design, similar to
  • after an answer is selected a transition to the next question occurs
  • title + intro text
  • around 10 questions
  • with 2 to 4 answers
  • each answer has a low and high amount of the estimated hours
  • optional choices are visible only after the minimum questions are answered

Current Progress:

I've added in week 1 - 4:

  • the questions
  • the answers
  • the values of the answer estimates
  • showing the estimate
  • extra step for input on details, name and email
  • not so bad design
  • a start button to start
  • email notifications
  • terms of service, privacy policy & cookie usage
  • styling it so it works on all devices (iphone 5 & 6 as well) (used bootstrap)
  • styling it so it looks the same on all devices (button changes now)

I've added in week 5 - 6:

  • slack notifications
  • analytics


  • a list of features as additional option within the raw estimate phase
  • a list of categories
  • a simple way to add those features to the estimate
  • a simple way to add more features

After that:

  • improve the focus on one question at a time
  • improve transition to next or previous question
  • see progress bar


  • add deadline(s)
  • add option to upload file(s) (design & background information)
  • add expected usage options to calculate hosting
  • add low and high costs for maintenance

Further research: