jyotisha and the sky
What is the Adhika Masa (leap month) and how is it determined in the Hindu calendar?
What it is and why it exists
The Hindu calendar follows the moon for its months but the sun for its seasons and festivals. A lunar year of twelve months runs about eleven days shorter than a solar year. Left alone, the two drift apart. Adhika Masa is the fix. An extra month is inserted to pull them back into alignment. This happens roughly every thirty-two and a half months, so about once every two to three years.
How it is calculated
The key is the Sankranti, the moment the sun moves from one zodiac sign into the next. This happens once a month in the solar calendar. A normal lunar month always contains one Sankranti. Occasionally a lunar month passes without any Sankranti falling inside it. When that happens, that month has no solar identity of its own. It is declared Adhika, meaning extra or additional. It takes the name of the month that follows it. So if the regular month of Ashadha comes next, the extra month is called Adhika Ashadha. Traditional astronomical texts including the Surya Siddhanta and the Karana Kutuhala lay out the detailed calculations behind this.
What the tradition says about it
Adhika Masa sits in an unusual place in the tradition. It is generally seen as inauspicious for major life events. Weddings, thread ceremonies, and other big rituals are usually not held during this month. At the same time, it is considered especially good for devotional practices. Prayer, fasting, charity, and reading sacred texts are all seen as carrying extra merit during this period. Some traditions call it Purushottama Masa, linking it to Vishnu, and hold it in high regard for that reason. So the month carries two faces at once, ordinary life paused, spiritual life deepened.
Today
Families in different regions handle Adhika Masa in different ways. Some follow the restrictions closely. Others observe only the devotional side. For the Hindu diaspora, it can be a confusing month because different community calendars and priests may mark it slightly differently depending on the regional tradition they follow. The core idea stays the same everywhere: it is a corrective month, a pause built into the calendar to keep time honest.