Why this tool does not pick a date for you
Every rule this engine applies elsewhere carries a citation to the work and the page it came from. That is the standard the site holds itself to, and it is what lets a reader check a verdict instead of trusting one. The lists that decide which nakshatras, tithis and weekdays a tradition accepts for a marriage could not be brought up to that standard without inventing references, so they are not implemented here.
The alternative — printing an auspiciousness verdict with no citable rule behind it — is the exact practice this site exists to argue against. It would also be very easy to do, which is rather the point.
What you get instead
Sixty days of computed panchang from whatever date you choose: the nakshatra and pada, the tithi and paksha, the vara and its lord, the nitya yoga and the karana. These are the values a practitioner will ask you for, and they are the same values a printed panchang carries, derived from the same positions the rest of the engine uses.
Two further columns are pure astronomy with no tradition attached. The Sun’s rashi is what the Kharmas or Malamasa window is defined by, so you can see when the Sun enters and leaves Dhanu or Meena without anybody telling you what to conclude. The separations of Jupiter and Venus from the Sun are what a combustion judgement is measured on — the degrees are given, and the orb at which a body counts as combust is left to whoever is applying it, because that threshold is a convention and conventions differ.
Why some rows say a value “turns over”
The Vedic day runs from sunrise to sunrise, not from midnight, and a tithi or nakshatra can change part-way through it. This engine does not compute sunrise, so rather than pretend to a precision it does not have, each day is sampled twice — early and late — and any value that differs between the two readings is flagged along with both values.
For a date being seriously considered, that flag is the useful part. A day whose nakshatra holds from one sampling to the other is stable whatever convention is used. A day where it turns over needs a proper sunrise-based reckoning before anybody relies on it, and knowing which days those are saves the conversation.
How to use this with an astrologer
Bring the sheet rather than a question. A practitioner choosing a date will work from exactly these values, and arriving with them computed removes the step where two people disagree about what the panchang said before they get to disagreeing about what it means. Where a date matters, ask which rule makes it suitable and which work that rule comes from — the same question worth asking of any astrological verdict, set out in how to read a matching report.
Two things worth keeping separate while you do it. Choosing a date is a different discipline from matching two charts, with its own literature and its own disagreements; a good match does not imply a good date and a difficult one does not forbid it. And a date being auspicious under a tradition is a statement about that tradition, not a prediction about a marriage — the boundary this site keeps everywhere, published in what we do not predict.
If you only need one date
Use the single-date panchang, which reports the same five limbs for one day with more detail around them. This tool exists for the case where a family is comparing a season rather than checking a day, which is when a list is more useful than a page.