Yoga: the Sun and Moon combination
In the Panchang, a yoga is one of 27 divisions made by adding the Sun's and Moon's longitudes, each covering 13 degrees 20 minutes. It is not the exercise.
Not the exercise
In a Panchang, yoga = union or combination. It has nothing to do with postures or meditation. It is one of the five limbs, and it describes a particular relationship between the Sun and the Moon.
How a yoga is calculated
Take the longitude of the Sun and the longitude of the Moon on the sidereal zodiac, and add them together. Divide the total into 27 equal parts of 13 degrees 20 minutes each. The part the sum falls in is the current yoga.
The Sun moves about one degree a day and the Moon about thirteen, so the sum grows by roughly fourteen degrees a day. A yoga therefore lasts about a day, though not exactly. It can begin and end at any hour. The site shows the exact start and end time in your local time.
This calculation uses the Lahiri (Chitrapaksha) ayanamsa, because longitudes are sidereal. The 27 yogas are sometimes called nitya yogas = daily yogas, to separate them from other combinations described in horoscope astrology.
The 27 yogas
The "nature" column gives a one-word summary of the common view. Sources disagree on a few of them. Vishkambha and Vajra are called mixed in some lists and unfavourable in others, and one list treats Ayushman as weak in its first hours. Use these labels as a general guide only.
| No. | Yoga | Nature |
|---|---|---|
| 1 | Vishkambha | Mixed |
| 2 | Priti | Favourable |
| 3 | Ayushman | Favourable |
| 4 | Saubhagya | Favourable |
| 5 | Shobhana | Favourable |
| 6 | Atiganda | Unfavourable |
| 7 | Sukarma | Favourable |
| 8 | Dhriti | Favourable |
| 9 | Shula | Unfavourable |
| 10 | Ganda | Unfavourable |
| 11 | Vriddhi | Favourable |
| 12 | Dhruva | Favourable |
| 13 | Vyaghata | Unfavourable |
| 14 | Harshana | Favourable |
| 15 | Vajra | Mixed |
| 16 | Siddhi | Favourable |
| 17 | Vyatipata | Unfavourable |
| 18 | Variyana | Favourable |
| 19 | Parigha | Unfavourable |
| 20 | Shiva | Favourable |
| 21 | Siddha | Favourable |
| 22 | Sadhya | Favourable |
| 23 | Shubha | Favourable |
| 24 | Shukla | Favourable |
| 25 | Brahma | Favourable |
| 26 | Indra | Favourable |
| 27 | Vaidhriti | Unfavourable |
The names are spelled in several ways, for example Shoola for Shula, Preeti for Priti, and Variyan for Variyana. Siddhi (number 16) and Siddha (number 21) are two different yogas, and some web lists wrongly show Siddha twice.
Which are traditionally avoided
Most traditions treat Vyatipata and Vaidhriti as the two yogas to avoid for new beginnings. Other unfavourable yogas, such as Atiganda, Shula, Ganda, Vyaghata and Parigha, are given less weight in daily life, and many families do not check them at all.
Do not read these labels as predictions of bad luck. They are a traditional way of choosing a quieter time for starting something important. Ongoing work and daily life do not need to stop.
What the site shows
The site shows the yoga of the day together with its exact start and end time. Because the yoga changes about once a day at an arbitrary hour, two yogas may fall on the same civil date. If you are planning a ceremony, look at the yoga at the time you intend to begin.
Different regions treat the importance of yoga differently. It carries less weight than the tithi and nakshatra for most festivals. Where it matters for a specific muhurat, your priest will tell you.