Overview
The Indian Calendar System, Mapped Out
"The Indian calendar" isn't one calendar — it's a family of related systems, some solar, some lunisolar, some regional. Here's how the pieces fit together.
Two eras (year-counting systems)
Vikram Samvat — the traditional era, ~57 years ahead of Gregorian, dominant in North Indian and Nepali civil/religious use.
Shaka Samvat — the era behind India's official National Calendar, ~78 years behind Gregorian, used in government contexts.
One repeating cycle
Samvatsara — a 60-year named cycle tracking Jupiter's position, running independently alongside both eras above.
Two calendar "modes"
Lunisolar — most religious festival dates (Diwali, Holi, Janmashtami) follow the Moon, with an occasional leap month keeping them anchored to season.
Solar — several regional New Year calendars (Tamil, Bengali, Odia, Punjabi and more) track the Sun directly, landing on a fixed date most years.
The five daily measurements (Panchanga)
Underneath all of this, every single day is measured by five elements: Tithi (lunar day), Vara (weekday), Nakshatra (lunar mansion), Yoga (Sun-Moon angle) and Karana (half-Tithi) — collectively the Panchanga.
Twelve months, six seasons
The lunar year runs through 12 Sanskrit months (Masa), grouped into 6 Ritus (seasons) of two months each.