FTL Calculator is a tool that helps you planning Crew duties with accordance to Operators Flight Times and Duty Limitations.
It is located in the Menu pannel under icon.
As you can see in the screenshot, it takes the following values into consideration:
Basic duty is calculated for both Single Crew (if applicable) and Multi Crew. This includes reporting and post-flight duty times.
Latest time on blocks is the latest time allowed for Block On. This is Basic duty reduced by the check out time.