The most common calendars are-

1. Vikrama Calendar- luni-solar calendar, followed in west and north India

2. Shalivahana or Sakha calendar- luni-solar calendar, followed in south India.

There are other regional variations, including a solar calendar followed in Tamil Nadu and Kerla, but the above two are the most spread nowadays.

We will explain hereby the basics of the lunar (luni-solar) Vedic calendar and we will mention the differences between north and south calendars.

Please note: the dates anf festivals in this website are according to Vikrama calendar, followed by our Parampara.

what is a luni-solar calendar?

A purely solar calendar, is a calendar in which a year is defined as the time required for the earth to complete one orbit around the sun. this period is 365 days, 5 hours, 48 minutes, 45.51 seconds. Dividing this period into twelve, we get the solar month- 30 days, 10 hours, 29 minutes, 3.8 seconds.

The Gregorian calendar is an example of a purely solar calendar.

A purely lunar calendar, in which a year is the time required to the moon to complete 12 orbits around the earth. this period is 354.37 days. The Islamic calendar is an example of a purely lunar calendar. the feature of the lunar calendar is that has no connection with the seasons, since the lunar year is shorter then the solar year, the lunar calendar is going "back" season-wise every year in 11-12 days, and will come back to the same relation it has with the solar year approximately every 33 years. (that means that the same holiday can be once in the summer and after a few years- in the summer. The Islamic calendar is an example of a purely lunar calendar.
 

A luni-solar calendar is a calendar in which a year is defined by twelve lunar orbits around the earth but it order that the seasons will not drift every year, an extra month is added every two or three years. The Vedic Hindu Vikrama and Sakha calendars,  are examples of luni-solar calendars(as well as the chinese and the Jewish calendars and many other ancient calendars).

Structure of the Vedic Hindu calendar.

Day

The day starts with the sunrise, and ends in the sunrise of the next day.

each day consists of five characters:

Month

the months start and end according to the position of the moon.

There are twelve months in the Hinu calendar.Each month divided into two Pakshas or fortnights. Each one is of 15 days.

The first half is called Krisna- the dark half, when the moon is getting smaller. The 15th day of this half is called Amavasya- no moon day.

The other half called Shukla- the brighter half, when the moon is getting bigger. The 15th day of this half is Purnima- full moon day.

Year

The year has twelve months, and every two or three years, and extra month (adhika maas) is added. the extra month is bearing the name of the previous month.

The names of the 12 months are: