Ananda Family
Why does Diwali move every year while Makar Sankranti stays near 14 January? Why do two panchangs give two dates? The Hindu calendar follows both the Moon and the Sun. These ten facts explain how it works.
1. The Hindu day begins at sunrise
In the Hindu calendar, the day begins at sunrise, not at midnight. Whatever tithi is running at sunrise gives its name to the whole day.12
Why it matters today: this is why an Ekadashi fast may start on a different date than you expect.
2. A tithi is not a day
A tithi is the time the Moon takes to move 12 degrees ahead of the Sun. A lunar month has 30 tithis: 15 in the bright half and 15 in the dark half.2
A tithi lasts about 23 hours and 37 minutes on average. But it can be as short as about 20 hours or as long as about 27 hours.2
3. A tithi can be skipped or come twice
Sometimes a tithi starts and ends between two sunrises. Then it is skipped in the day count. Sometimes a tithi is still running at the next sunrise. Then it covers two days.2
Why it matters today: this is why your family may see one festival marked on two days.
4. Your city can change the date
Sunrise and Moon timings change with place. So Ekadashi can fall a day apart in India and abroad. Families outside India should check a panchang made for their own city.3
5. An extra month comes about every three years
A lunar year has about 354 days. A solar year has about 365 days. To stay in step with the seasons, an extra month is added about every 32.5 months.4
This month is called Adhik Maas or Purushottam Maas. An extra Kartik month is very rare. Between 1901 and 2150, it happens only once, in 1963.4
6. North and South end the month differently
In the amanta system, a month ends on Amavasya, the new moon. Gujarat, Maharashtra, Goa, Karnataka, Andhra Pradesh and Telangana follow it. In the purnimanta system, a month ends on Purnima, the full moon. Nepal and most of North India follow this.1
Why it matters today: the same festival can fall in a month with a different name, depending on where your family comes from.
7. A panchang has five limbs and 27 nakshatras
Panchang means five limbs. They are tithi, the solar day, nakshatra, yoga and karana. Karana is half a tithi.1
The sky is divided into 27 nakshatras. Each one covers 13 degrees and 20 minutes of the Moon's path.1
8. Our weekdays are named after the Sun, Moon and planets
Ravivar is the Sun's day and Somvar the Moon's. Then come Mangalvar for Mars, Budhvar for Mercury, Guruvar for Jupiter, Shukravar for Venus and Shanivar for Saturn.1
9. India has an official national calendar most people never use
India's national calendar is based on the Saka era. It started on 1 Chaitra 1879 Saka, which was 22 March 1957. A committee led by the scientist Meghnad Saha suggested it.5
It is used by the Gazette of India, All India Radio and government calendars. But most panchang makers and families never took it up.5
Another old system, Vikram Samvat, is usually 57 years ahead of the English calendar. In Nepal it is an official calendar.6
10. Makar Sankranti follows the Sun, so its date stays steady
Most festivals follow the Moon, so their dates move. Makar Sankranti follows the Sun. It marks the Sun entering Makar, so it falls on 14 January, or 15 January in some years.7
Over centuries even this date slowly drifts. Makar Sankranti and the winter turning of the Sun last fell together in 291 CE.7
Why it matters today: our calendar is a way of reading the sky. Every date carries the Sun, the Moon and the seasons together.7
🙋 Questions families ask
Why do Hindu festival dates change every year?
Most follow the Moon. A lunar year is about 11 days shorter than a solar year.
Why is a festival sometimes on two days?
A tithi can run across two sunrises, or panchangs for different places can differ.
What is Adhik Maas?
An extra lunar month added about every three years to stay in step with the seasons.
Keep our roots alive at home
Ananda Family helps you explore Hindu stories, festivals and samskaras, with a daily mantra and an evening story practice for your family.