How Rahu Kaal is calculated

The calculation has three steps and needs only the sunrise and sunset of the place and the weekday.

Step 1: find sunrise and sunset

Use the local sunrise and sunset for that day, in local clock time. Panchang makers use the moment the upper edge of the sun appears and disappears, with the usual allowance for the bending of light in the air. Our tool works these out from astronomical formulas for each city and date, accurate to about a minute.

Step 2: cut the day into eight equal parts

Subtract sunrise from sunset to get the length of the day, and divide by eight. For a day from 6:00 to 18:00 the day is 12 hours and each part is 90 minutes. For a short December day in Delhi, from about 7:05 to 17:30, the day is 10 hours 25 minutes and each part is about 78 minutes.

Step 3: take the weekday's part

A memory aid in common use for Rahu Kaal is the order Monday, Saturday, Friday, Wednesday, Thursday, Tuesday, Sunday, which runs through the parts 2, 3, 4, 5, 6, 7, 8.

Worked example

Take a Tuesday with sunrise at 6:40 and sunset at 18:10. The day is 11 hours 30 minutes, which is 690 minutes; one eighth is 86 minutes 15 seconds. Tuesday uses the seventh part. It starts after six parts, at 6:40 plus 517.5 minutes, which is 15:17:30, and ends 86 minutes 15 seconds later, at 16:43:45. So Rahu Kaal is about 15:18 to 16:44.

Why the answer differs between sources

Some printed calendars simply assume 6 am to 6 pm for every place and every day, which is easy but can be 20 to 30 minutes off. Some panchang makers use the sunrise of the nearest big city, and a few start the day at a conventional time or count the parts from a different starting point. Where a family follows a particular panchang, follow that one. Our times use the true sunrise and sunset of the city you choose.

Try it for your city on the home page, or open one of the weekday pages to compare many cities side by side.

Questions people ask

Find Rahu Kaal for your city