Rahu Kaal

Every panchang's most famous warning. Rahu Kaal is one-eighth of the daylight, marked out for Rahu — the shadow planet of obstruction — on each day of the week. Work begun inside it is traditionally said to meet avoidable obstacles, so calendars print it and travellers plan around it.

The calculation takes seconds. Divide the span from local sunrise to local sunset into eight equal parts; the part belonging to that weekday is Rahu Kaal. The weekday order never changes — 2nd part Monday, 3rd Saturday, 4th Friday, 5th Wednesday, 6th Thursday, 7th Tuesday, 8th Sunday — but the duration of each part does, growing with summer days and shrinking in winter. That is why the window lands in the early morning on Mondays but eats the late afternoon on Sundays, and why no fixed clock time is ever correct.

Worked example: Delhi in late October, sunrise 6:20 am, sunset 5:40 pm — ten hours twenty minutes of daylight, each eighth about 77.5 minutes. On a Wednesday (5th part) Rahu Kaal runs from about 11:07 am to 12:25 pm. The same Wednesday in June, with 14 hours of daylight, stretches each part to 105 minutes and moves the window to roughly 1:25–3:10 pm. Same weekday, different city and season, entirely different hours.

What it governs is beginnings, not life itself. Signing contracts, launching ventures, starting journeys and first-use rituals are the classic items to move outside the window; ordinary routines, travel home and work already underway are unaffected. Many traditions add a curio: because the hour belongs to Rahu, it is considered a fine time to propitiate Rahu — or Durga — precisely when everything else hesitates.

Rahu Kaal is one of several daily windows, alongside Yamaganda, Gulika Kaal and Dur Muhurat, and the best known rather than the most severe. Any panchang app or the Daily Rashifal tool lists it by city and date.