Ja'fari prayer times: how they work

Every timetable starts with the sun: dawn, true noon, a shadow ratio for the afternoon, sunset and the disappearance of twilight. Those events are astronomical and can be computed precisely for a set of coordinates.

What is not purely astronomical is which moment counts. That is where conventions and jurisprudence enter, and it is why two accurate calculators can produce two different timetables for the same street.

A calculation method is a package of parameters: the solar depression angle used for dawn and for night, the treatment of the afternoon shadow, and any adjustment applied around sunset. Profiles associated with Tehran and with Qum are commonly offered by Shia prayer-time services.

A calculated timetable is an aid. Where a marja or a local centre gives specific guidance, that guidance takes precedence over any number on a screen.

Times are computed in solar terms and then expressed on your local clock. A wrong timezone or a missed daylight-saving change is the most common cause of a timetable being an hour out.

This is an educational summary drafted editorially and awaiting scholarly review. It is not a personal religious ruling; your marja's guidance and your local religious authority take precedence.