Understand the traditional Rahu Kalam calculation from local sunrise and sunset, eight daylight segments and the weekday mapping.
Rahu Kalam - also written Rahu Kaal, Rahu Kala or Rahu Kaalam - is a daily period used in Hindu calendrical and astrological traditions. Its timing is derived from the weekday and the length of local daylight.
The Bethemesh Rahu Kalam calculator applies that method to a specific date and place. The calculation itself is straightforward once the sunrise and sunset are known.
The method starts with the day’s sunrise and sunset, not a fixed timetable.
daylight duration = sunset − sunriseThe daylight duration is then divided into eight equal parts:
segment duration = daylight duration ÷ 8Segments are therefore longer in long summer days and shorter in winter.
Under the convention used by Bethemesh and documented by Drik Panchang, the Rahu Kalam segment is:
| Weekday | Segment |
|---|---|
| Monday | 2nd |
| Saturday | 3rd |
| Friday | 4th |
| Wednesday | 5th |
| Thursday | 6th |
| Tuesday | 7th |
| Sunday | 8th |
The first daylight segment is not used in this sequence.
Imagine a theoretical day with sunrise at 06:00 and sunset at 18:00. Daylight is 12 hours, or 720 minutes.
720 ÷ 8 = 90 minutes per segmentOn Monday, the second segment would run approximately from 07:30 to 09:00.
That familiar 90-minute pattern only works for a 12-hour day. If sunrise is 05:40 and sunset is 21:20, each segment is much longer.
Sunrise and sunset depend on latitude, longitude, date and civil time zone. Two cities in the same country can therefore produce different times, and the difference becomes larger across distant regions or latitudes.
The calculator searches a city or uses your position, obtains the location coordinates and time zone, then computes the solar boundaries needed for the eight-part division.
You may see tables that assign a standard clock interval to each weekday. Such tables usually assume an idealised day of about twelve hours.
They are useful for remembering the segment order, but they cannot reproduce seasonal changes in sunrise and sunset. A date-and-location calculation is more faithful to the eight-segment method when a precise local time is needed.
Bethemesh calculates the time interval associated with this traditional convention. It does not attempt to prove or disprove religious or astrological beliefs about what should be done during that period.
Practices and interpretations can vary by region and tradition. The output should therefore be read as a calendrical/solar calculation applied to a stated convention.
Rahu Kalam is only one element found in broader Panchang systems. A full Panchang may also include tithi, nakshatra, yoga, karana and other timings.
Rahu Kalam is a useful standalone calculation because its inputs and method are compact: two local solar events, eight equal daylight segments and a weekday lookup.
Rahu Kalam is not a fixed clock time. A precise calculation needs the date, location and weekday. Find sunrise and sunset, split daylight into eight equal parts, then select the weekday’s segment.
No. Ninety minutes corresponds to a twelve-hour daylight period. The actual duration is one eighth of local daylight.
Because local sunrise and sunset change with geographic position.
Yes for expressing the result as local clock time. The calculation therefore needs the time zone associated with the selected place.
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