The daily sunrise-to-sunset span is divided into eight equal parts. Each part is ruled by one of the eight planets including Rahu. The part ruled by Rahu is called Rahu Kalam — about 1.5 hours of "shadow time" each day, considered inauspicious for new beginnings.
How it is computed
Take the full daytime (sunrise → sunset) and divide it by 8. Rahu's slot is at a fixed ordinal position depending on the weekday:
| Day | Rahu's slot | Approx clock time (12h day) |
|---|---|---|
| Monday | 2nd of 8 | ~ 07:30 – 09:00 |
| Saturday | 3rd of 8 | ~ 09:00 – 10:30 |
| Friday | 4th of 8 | ~ 10:30 – 12:00 |
| Wednesday | 5th of 8 | ~ 12:00 – 13:30 |
| Thursday | 6th of 8 | ~ 13:30 – 15:00 |
| Tuesday | 7th of 8 | ~ 15:00 – 16:30 |
| Sunday | 8th of 8 | ~ 16:30 – 18:00 |
The Telugu / Tamil mnemonic to remember the order is "Mother Saw Father Wearing The Turban Suddenly" — Monday-Saturday-Friday-Wednesday-Thursday-Tuesday-Sunday, slots 2 through 8.
What Rahu Kalam affects
Routine work — eating, working, travelling, meeting people — is fine in Rahu Kalam. What is avoided:
- Starting a new venture, signing contracts.
- Marriage rituals, housewarming.
- Beginning a journey for an important purpose.
- Religious / yajna work.
How the filter works
Rahu Kalam is a skip-inside filter. The two states are:
- Yes — slot falls inside Rahu Kalam.
- No — slot falls outside Rahu Kalam.
Default keeps both. To exclude Rahu Kalam from results, uncheck "Yes". Most users keep this on by default.