Why do birthdays and festivals in india don't coincide every year?

I realized that the birthdays and festivals in India don't coincide every year. The calendar is referred for festivals and birthdays are different. Festivals in India are celebrated as per the Indian calendar, while birthdays are celebrated as per the English calendar. An ancient tradition in India was to celebrate birthdays as per Indian calendar. This is known as janmatithi. Visit the website janmatithi.com to know more