Rahu Kaal: what it is and how it is calculated
Rahu Kaal is a daily period of about 90 minutes, traditionally considered inauspicious for starting new activities. Its position depends on the weekday.
What it is
The day from sunrise to sunset is divided into eight equal parts, and Rahu Kaal is one of them. The part for each weekday is fixed: Sunday 8th, Monday 2nd, Tuesday 7th, Wednesday 5th, Thursday 6th, Friday 4th and Saturday 3rd.
How it is worked out or read
The panchang tool computes Rahu Kaal from the local sunrise and sunset of the chosen city. The part is one eighth of the daylight length, starting at the position for the weekday.
Where it appears on this site
Rahu Kaal is shown in the panchang. The Abhijit article describes the opposite, a favourable midday window.
How Rahu Kaal is found
Rahu Kaal is one of the eight equal parts of the daylight, and which part it is depends on the weekday. The daylight is divided into eight equal parts, and the part for each weekday is fixed: the eighth for Sunday, the second for Monday, the seventh for Tuesday, the fifth for Wednesday, the sixth for Thursday, the fourth for Friday and the third for Saturday. Each part lasts about ninety minutes in a twelve-hour day.
Why the period is avoided
The traditional reason for avoiding Rahu Kaal is that Rahu is considered inauspicious in the Jyotish scheme, and its daily window is read as a time when new beginnings are less favoured. Many families avoid starting a journey, a contract or a new task during this window. The practice is cultural as well as astrological, and a reader can respect it while understanding its origin.
Checking Rahu Kaal in practice
To check Rahu Kaal for a given day, use the panchang for the city, which gives the window from the actual sunrise and sunset. The window is the same length every weekday in a given season, but its position changes with the weekday. A planner who wants to avoid it should check the window for the exact day rather than assume a fixed clock time.
Rahu Kaal in travel and work
Travellers and employers often use Rahu Kaal as a reason to adjust the time of a departure or a start, rather than to cancel the day. A journey that would begin in the window can often leave a little earlier or later without any real cost, and a meeting can be moved to the window that follows. The practical habit is to look at the day's window before fixing a time, and to treat it as one more constraint to fit around the other arrangements.
Some households keep a simple card with the weekday windows for the season. Because the position of the window follows the weekday, the card can show at a glance which hours to avoid for the coming week, and it saves checking the panchang for each day separately.
What the window does not decide
Rahu Kaal is a traditional window, and it does not decide whether an activity will succeed. A task started inside the window may go well, and one started outside it may not. The reader should keep the window in proportion, as one traditional factor among many, including the person's preparation, the other people involved and the practical conditions of the day. The window is a convention for timing, and its value lies in the reassurance it gives the people who observe it.