How Rahu Kaal is calculated, and why it differs by city

Rahu Kaal is calculated by dividing the time between local sunrise and local sunset into eight equal parts and taking one of them, chosen by the day of the week. Because sunrise and sunset differ from city to city and from season to season, the length and position of Rahu Kaal differ too. A fixed chart that gives the same clock times everywhere is an approximation, and often a poor one.

If you only want today's answer, the live Rahu Kaal tool shows whether it is running right now for your city. The rest of this page explains how that answer is reached.

The rule in one paragraph

Take the length of the day, from sunrise to sunset, in minutes. Divide by eight. That is the length of one part. Rahu Kaal is a particular part depending on the weekday:

• Monday: the 2nd part
• Saturday: the 3rd part
• Friday: the 4th part
• Wednesday: the 5th part
• Thursday: the 6th part
• Tuesday: the 7th part
• Sunday: the 8th part

Read down that list and the part number climbs by one each step: Monday, Saturday, Friday, Wednesday, Thursday, Tuesday, Sunday. The first part of the day is never Rahu Kaal. A common mnemonic is "Mother Saw Father Wearing The Turban Suddenly".

Yamaganda and Gulika use the same eighths

Two other periods are taken from the same eight-way split, and most almanacs print all three together.

Yamaganda (Yamagandam in Tamil) falls on the 1st part on Thursday, 2nd on Wednesday, 3rd on Tuesday, 4th on Monday, 5th on Sunday, 6th on Saturday and 7th on Friday.

Gulika (Kuligai in Tamil) falls on the 1st part on Saturday, 2nd on Friday, 3rd on Thursday, 4th on Wednesday, 5th on Tuesday, 6th on Monday and 7th on Sunday.

Because all three are eighths of the same day, they never partly overlap. On any given day they occupy three different whole parts.

A worked example: Calgary, Saturday 17 October 2026

Calgary that day has sunrise at 08:04 and sunset at 18:37.

• Day length: 18:37 − 08:04 = 10 hours 33 minutes = 633 minutes
• One part: 633 ÷ 8 = 79.125 minutes, call it 79
• Saturday's Rahu Kaal is the 3rd part: it starts after two parts, 08:04 + 158 minutes, and ends one part later
• Rahu Kaal: 10:43 to 12:02
• Gulika, Saturday's 1st part: 08:04 to 09:23
• Yamaganda, Saturday's 6th part: 14:40 to 15:59

The minutes are rounded for display. The site works from sunrise and sunset to the second, which is why adding 79 minutes by hand can occasionally land one minute away from the printed figure. You can see the full day for that city on the Calgary Rahu Kaal page.

Why the popular fixed chart is wrong for most people

You will often see a chart giving Rahu Kaal as 07:30–09:00 on Monday, 15:00–16:30 on Tuesday, 12:00–13:30 on Wednesday, and so on. Those figures are not invented; they are what the rule produces if sunrise is exactly 06:00 and sunset exactly 18:00. A twelve-hour day divides into eight parts of 90 minutes, and Monday's 2nd part is then 07:30 to 09:00.

The trouble is that almost nobody has a 06:00 sunrise and an 18:00 sunset on an ordinary day. Compare the Calgary example: Saturday's chart value would be 09:00 to 10:30, while the computed value is 10:43 to 12:02. The chart is wrong by more than an hour and a half at the start, and the period is 11 minutes shorter than the chart assumes.

Three things that move Rahu Kaal

Latitude

Near the equator, day length stays close to twelve hours all year, so the fixed chart is roughly right apart from the offset of sunrise from 06:00. Singapore and Kuala Lumpur are good examples; compare Rahu Kaal in Singapore with Rahu Kaal in Kuala Lumpur. Further from the equator the day stretches in summer and shrinks in winter, and every part stretches and shrinks with it. In Calgary, London or Toronto, a midsummer Rahu Kaal is much longer than a midwinter one.

Longitude within a time zone

A time zone covers a broad band of longitude, but the Sun keeps local time. Two cities on the same clock can have sunrises tens of minutes apart. India uses a single time zone across a country nearly 3,000 kilometres wide, so sunrise in the north-east comes well before sunrise in the west. Rahu Kaal in Mumbai, Delhi and Chennai are not the same, even though all three use IST.

Daylight saving time

In countries that change the clocks, Rahu Kaal moves an hour on the clock overnight. Nothing astronomical has happened; the Sun rises at the same moment it did the day before, but the clock reads differently. Because the calculation starts from the actual sunrise, it follows the change automatically. Toronto, New York and London all show this twice a year.

What "sunrise" means in the calculation

Almanacs differ slightly on what counts as sunrise. The common convention, and the one used here, is the moment the upper edge of the Sun's disc appears on a flat horizon, allowing for atmospheric refraction. Some traditional almanacs use the centre of the disc instead. The difference is a minute or two, which is why two reputable sources can disagree on Rahu Kaal by about that much. It is not worth worrying about.

What Rahu Kaal is traditionally used for

The tradition treats Rahu Kaal as a poor time to begin something new: a journey, a purchase, a signature, a ceremony. It is not held to be dangerous, and it says nothing about activities already under way. Work, travel and ordinary life carry on through it. If you have flexibility over when to start something, avoiding a 79-minute window costs very little. If you do not, the period is not a reason to miss an appointment. For more on where timing helps and where it is oversold, see what muhurta can and cannot tell you.

The classical rule is a daytime rule, and the site computes daytime Rahu Kaal. Some almanacs also print a night-time version; it is less widely followed.

Frequently asked questions

Is Rahu Kaal always 90 minutes?

No. It is one-eighth of the daylight, so it is 90 minutes only when the day is exactly twelve hours long. In the Calgary example it is 79 minutes. In a northern summer it can exceed two hours.

Why does my calendar show a different Rahu Kaal from this site?

Usually because the calendar uses a fixed chart, or was printed for a different city. A calendar printed for Chennai will be wrong in Singapore or Brampton. Small differences of a minute or two come from how sunrise is defined.

Does Rahu Kaal start at midnight or at sunrise?

At sunrise. The Hindu day runs from sunrise to sunrise, and Rahu Kaal is counted within the daylight portion.

Are Yamaganda and Gulika as important as Rahu Kaal?

Most almanacs list all three as periods to avoid for new beginnings. Rahu Kaal is the most widely observed, and Gulika is sometimes treated differently (some traditions hold that what starts in Gulika repeats). Practice varies by region and family.