Hindu Calendar vs Gregorian Calendar: Complete Guide

The Gregorian calendar is solar: it tracks the Earth's orbit around the Sun. The Hindu calendar is lunisolar: months follow the Moon, but an extra month (Adhik Maas) is added roughly every three years to stay aligned with the seasons.

Tithi

A tithi is the time it takes for the Moon to gain 12 degrees on the Sun. There are 30 tithis in a lunar month, split into Shukla Paksha (waxing) and Krishna Paksha (waning). A tithi can start at any time of day, which is why festival dates are fixed by the tithi prevailing at sunrise.

Amanta and Purnimanta

In the Amanta system months end on the new moon; in the Purnimanta system, used in most of north India, they end on the full moon. The same day can therefore carry different month names in different regions.

Eras

Vikram Samvat runs about 57 years ahead of the Gregorian year, and Shaka Samvat, the official national calendar of India, runs about 78 years behind it.