What is zawāl time?

Zawāl is the moment the sun passes the meridian - true solar noon, when the sun begins its decline from the highest point of its arc. The few minutes immediately before it, while the sun "stands" at its zenith (istiwāʾ), are one of the three strict times in which prayer is withheld; once zawāl has passed, the prohibition ends and the time of Dhuhr enters. Two practical points: zawāl is an astronomical event that shifts daily and by longitude, so it cannot be read off a fixed clock time; and mosque adhans are often delayed past the actual entry, so this tool computes the zenith window from the solar transit itself, never from a timetable.

Rulings differ by madhhab and by what you intend to pray - the live answer below is conditioned on both. Draft pending scholar verification; see the methodology.