FlightTime Calc is a flight time calculator, that helps you calculate your flight hours. It has the ability to add and subtract times, in the hh: mm: ss or hh. Ddddddd format. The result is shown in (hh: mm: ss) Time Format or in (hh. Ddddddd) Hours Format, with seven (7) decimal digits (e. G. 1. 5000000 means one and a half hour).