When is Vat Savitri Amavasya?

How this date is worked out

A festival is a position, not a date. The lunar month is named by the sidereal sign the Sun stands in at the new moon that opens it, and the tithi is the Moon's distance from the Sun in twelve-degree steps. Both come from the same ephemeris this site casts birth charts with.

North India reckons a month from full moon to full moon, so the dark fortnight carries the next month's name — the same day is Shravana Krishna Tritiya in Pune and Bhadrapada Krishna Tritiya in Delhi. These dates use the northern reckoning, and the tithi is printed above so there is nothing to take on trust.

The sky has a calendar. So do you.

The same engine reads your own birth moment — every house, every graha, every period with dates.