Hindu date converter
Both ways: a Gregorian date to its tithi, month and samvat, or a Hindu date (Vikram or Shaka) to the Gregorian day, by the sunrise rule for your city.
Questions
Why can a tithi fall on two dates or none?
A tithi is counted for the day on which it is current at local sunrise. A long tithi can span two sunrises (vriddhi); a short one can begin and end between sunrises (kshaya), in which case we show the day it begins.
Amanta or purnimanta?
North India counts a month from full moon to full moon (purnimanta); Gujarat, Maharashtra and South India from new moon to new moon (amanta). Shukla paksha has the same month name in both; Krishna paksha differs by one month.
When does the Vikram Samvat year change?
At Chaitra Shukla Pratipada (March/April) in the North Indian reckoning used here. Vikram = Shaka + 135.