Why your Vedic birthday isn't the same date every year
The Hindu calendar is lunar, not solar, so the day that actually recurs each year is your birth tithi — the lunar day fixed by the angle between the Sun and Moon — not the Gregorian date. Because a lunar year runs about eleven days short of a solar one, the tithi drifts against the civil calendar and lands on a different date almost every year.
How the recurrence is found
There is no formula that jumps straight to the answer, because the tithi does not advance by a fixed number of days. This tool scans forward from today, checking the tithi at each noon, until it finds the day your birth tithi is active — the same calculation used for Tithi Pravesha, the traditional lunar-return chart.
What to do with the date
The recurrence shown here is the day traditionally celebrated as a Hindu birthday — the tithi-varsha — and is also the date some families use to plan a satyanarayan puja or a birthday havan on the correct lunar day rather than the Gregorian one.
Common questions
What is a tithi birthday?
The Gregorian date on which your birth tithi — the lunar day you were born on — next falls, rather than the calendar anniversary of your birth date. It is the day traditionally marked as a Hindu birthday.
Why does it move every year?
A lunar year is about eleven days shorter than a solar one, so the tithi drifts steadily against the Gregorian calendar and lands on a different date almost every year, sometimes twice in the same solar year.
Why do you need my exact time and place of birth?
The tithi is fixed by the angle between the Sun and Moon at the moment of birth, and that angle changes through the day. The exact time and place is what fixes which tithi you were actually born on.