Adhik Maas: How the Hindu Calendar Adds a Month to Stay in Season

Adhik Maas is the extra month the Hindu lunisolar calendar inserts roughly every two and a half to three years to keep the lunar months aligned with the seasons - the reason Diwali stays in autumn and Holi stays in spring, year after year. It is often described as a religious curiosity, but at its core it is a piece of calendar engineering, driven by a precise astronomical rule that any panchang software can verify. 2026 is an Adhik Maas year, which is why the entire festival season arrived later than usual, and the mechanism deserves to be understood rather than merely accepted.

Two clocks that refuse to agree

The Hindu calendar runs on two natural clocks at once. The first is the moon: one lunar month is the span from one new moon to the next, about 29.5 days, and twelve of them make a lunar year of about 354 days. The second is the sun: the seasons repeat on the solar year of about 365.25 days. Those two numbers do not divide into each other, and no calendar can make them. The lunar year finishes about 11 days before the sun completes its circuit.

Left uncorrected, that gap compounds. Every year, each festival would slide about 11 days earlier in the seasons; within sixteen years or so, an autumn festival would be a summer one. This is exactly what happens in a purely lunar calendar such as the Islamic one, where months deliberately migrate through the seasons. The Hindu tradition chose the other path: keep the months lunar, but pin the year to the sun by occasionally adding a thirteenth month. When the accumulated shortfall approaches a full month - roughly every 32 to 33 months - an Adhik Maas absorbs it, and festivals snap back into their proper season.

The sankranti rule: how a month becomes adhik

What is elegant is that nobody decides when to insert the month. The sky does. The rule hinges on sankrantis - the moments the sun crosses from one sidereal rashi into the next. There are twelve sankrantis a year, spaced a bit over 30 days apart, while a lunar month runs about 29.5 days. Usually each lunar month contains exactly one sankranti, and that pairing gives the month its identity. But because the lunar month is slightly shorter than the gap between sankrantis, every few years a lunar month slips entirely between two of them and contains no sankranti at all.

That month is declared adhik - "additional". It takes the name of the month that follows, with the prefix Adhik, so the calendar shows the same name twice: first the Adhik month, then the regular (nija) one. In calendars that end the month at the full moon (purnimanta, the North Indian way), the adhik month still runs new moon to new moon, so it sits inside the month it is named after, between that month's dark and bright halves.

The month goes by several names: adhik maas (adhika masa in the south), Purushottam Maas, and mal maas. What households do with it:

• Ceremonies wait. Weddings, griha pravesh, upanayana and other muhurat-bound ceremonies are not held in it, and a festival that falls in that month's name is kept in the nija month that follows.
• Worship goes on. As Purushottam Maas it is kept for fasting, japa, scripture reading and daana.
• In Maharashtra it is called dhondyacha mahina, and families invite the son-in-law home and give him 33 anarse (a rice sweet) with a lamp.

There is a rarer mirror case: near the sun's fastest stretch of the year, a lunar month can contain two sankrantis, and a month is dropped - a kshaya maas. It is very rare: the last was in 1983, and the next is not due until 2124. A year with a kshaya maas also carries two adhik months, one before it and one after.

What happened in 2026

In 2026 the lunar month falling between mid May and mid June contained no sankranti, so it became Adhik Jyeshtha - an extra month inserted before the regular Jyeshtha. Every lunar-calendar festival after it was pushed roughly two to three weeks later in the civil calendar than the previous year: Raksha Bandhan slid to the end of August, Navratri deep into October, Diwali into November. If you have been comparing this year's dates against last year's and wondering whether something changed, nothing did - the calendar simply performed its scheduled correction. You can see the effect in our published date guides, such as the Pitru Paksha 2026 shraddha dates and the wedding muhurat dates for 2026-27, where the whole sequence sits later than a typical year.

A correction, not a glitch

It is worth pausing on what this system achieves. With one rule - a month with no sankranti is repeated - the calendar keeps its lunar months in step with its solar year by itself, without committees, leap-second debates or decrees; the Gregorian calendar needed a papal reform and the deletion of ten days in 1582 to fix its drift. The panchang's solar year, though, is counted against the stars (sidereal), and it is about 20 minutes longer than the year of the seasons, so festivals still drift slowly against the seasons, about one day in 71 years. That is why Makar Sankranti, once around 22 December, now falls on 14 January. Nineteen solar years contain almost exactly 235 lunar months, so the pattern of insertions repeats on a near-19-year cycle - the same rhythm Babylonian astronomers used from about 500 BCE, known today as the Metonic cycle after the Greek astronomer Meton.

The panchang on Purohit.app is computed from planetary positions using the Swiss Ephemeris, so the sankranti moments and month boundaries that decide an Adhik Maas come from the same calculation that runs the daily tithi and nakshatra. When your panchang names the month, the adhik logic is already inside it - the sky keeping its own books, as it always has.