Ekadashi in December 2028

In Delhi: Saphalā on Tuesday, 12 December; Putradā on Wednesday, 27 December.

Ekadashi is the eleventh tithi of each half of the lunar month, one in the bright half (Shukla) and one in the dark half (Krishna), so there are usually two a month. A tithi is the time the Moon takes to gain 12° on the Sun. Surya Siddhanta 2.64, 2.66

On the next day, while Dvādaśī lasts, since letting Dvādaśī pass unbroken is a grave fault: in the first three muhūrtas after sunrise, but not in Hari-vāsara, the first quarter of Dvādaśī. When Hari-vāsara outlasts those three muhūrtas, in the afternoon, never at midday. If no Dvādaśī is left at sunrise, on Trayodaśī. In a difficulty, water counts as breaking the fast. Dharmasindhu p. 19; Nirṇaya-sindhu pp. 70⁠–⁠71

The texts test the Ekadashi day for Dashami, the tithi before it. Smārtas test at sunrise; Vaiṣṇavas test the 96 minutes before sunrise, called aruṇodaya. When Ekadashi or Dvadashi runs long, or Ekadashi touches no sunrise, each tradition keeps its own day. Nirṇaya-sindhu pp. 53⁠–⁠63

Each date is worked out for the city’s own sunrise. A tithi begins and ends at the same moment everywhere, but the sunrise it is tested against differs, so a city far to the east or west can keep another day.

Gauḍīya Vaiṣṇava calendars follow the Hari-bhakti-vilāsa, which is not among our sources, so their dates can differ from the Nirṇaya-sindhu days shown here.