ఏకాదశి, గృహస్థు దృష్టిలో

Count tithis from the new moon and you meet the eleventh twice, once in the bright fortnight and once in the dark. That is Ekadashi as astronomy. What a person eats or does not eat on it is a vrata, and vratas are not uniform. A Smarta house, a Vaishnava house, and a house that simply skips onions because a parent asked, are three practices. Pocket Pandit will identify the tithi. It will not assign you a fast you did not bring from your own people.

The eleventh is also sometimes chosen for namakarana and for other rites, which is a different use of the same number. Context is the rite. The number is not an instruction by itself.

If two panchangs disagree by a few hours on when the tithi ends, the disagreement is usually the place, the sunrise rule, or the ayanamsha. Ask which. Do not call either of them faithless.