Flight Day/Night Calculator is a simple, reliable offline tool that makes calculating the exact time spent in day and night during a flight quick and accurate. It has been built by an airline pilot, for pilots at every stage of training and operation. Whether you’re logging your first night cross-country, building hours toward your CPL, or recording complex routes as a commercial or airline captain, this app gives you confidence in your logbook entries.

Many aviation authorities require pilots to log flight time split into day and night. For student pilots, PPLs, CPLs, and ATPLs (ATPs in US terms), this is often left to guesswork or rough estimation. Paper logbooks and electronic apps alike usually rely on you to calculate the split separately. Even when other apps include a day/night function, they often ignore taxi phases and assume a simple great circle route. Flight Day/Night Calculator handles both, with options to include taxi time and add waypoints for more accurate results. Everything works completely offline, with no data connection required.

The app calculates the aircraft’s position for every minute of the flight based on your departure, destination, and any optional waypoints. At each point it uses embedded astronomy algorithms to determine the sun’s elevation angle. By the internationally recognised definition of civil twilight, the app records day whenever the sun is above the horizon down to six degrees below, and night when it is lower. The result is a precise, minute-by-minute breakdown of your day and night time.

Features include:

* Direct ICAO code entry with name confirmation, or built-in airport search

* Airport lookup showing sunrise, sunset, MCT, and ECT on any date

* Optional waypoints (up to 20) to reflect actual routing, or stick to great circle for quick use

* Block time (OOOI) or airborne-only timing, with taxi transitions handled correctly

* Results in both hours/minutes and decimals for easy logbook entry

* Transition events with exact times and positions, plus optional sunrise/sunset events for validation

* Distance, average groundspeed, and calculated MCT/ECT for each airport

* Guardrails to prevent unrealistic inputs

Flight Day/Night Calculator is optimised for both iPhone and iPad, with a clear, distraction-free interface tailored to the way pilots plan and review flights. It is built to complement, not replace, your logbook or logbook app — making accurate day/night splits simple and dependable for any pilot who needs them.