Mundan, also called Chudakarana or Chaula, is the first tonsure ceremony, one of the sixteen Hindu samskaras, in which a child's birth hair is shaved for the first time. This finder scans the date range you give, for your city, and ranks the auspicious windows on the twelve nakshatras and four weekdays it holds for this rite, dropping every window that falls in Rahu Kaal, Yamaganda or Gulika Kaal.
Kalaprakasika Ch. V holds tonsure unfavourable while the Sun is in its southern course (Cancer through Sagittarius). No window is offered on those days.
Mundan (Chudakarana or Chaula) is traditionally performed in a child's odd year of age - most commonly in the first, third or fifth year - after which the birth hair is shaved and fresh growth begins. Many families schedule it around the first or third birthday, while some perform it earlier at a family temple according to their kula custom.
Classical texts favour the period when the Sun is in its northern course (Uttarayana) and during the bright fortnight (Shukla Paksha). The child's own birth month (Janma masa) and birth nakshatra are usually avoided. These are family-level and year-level rules that you apply when you choose which range to search; the finder itself works inside the range you give it.
A strong Mundan Muhurat pairs a favourable nakshatra with a supportive tithi and weekday, and, if you supply the child's birth star, a Moon that is well placed for the child by Tara Bala and Chandra Bala.
None of these decides the date alone. Each moves the day's score, and every result lists the factors that fired on it, so you can see whether a day ranked well on its nakshatra, its tithi, its weekday, or on the child's own Tara Bala and Chandra Bala when you have supplied a birth star.
It checks, for every day in your range: the tithi, the nakshatra against the twelve-star Mundan set, the weekday against the four favourable ones, the nitya yoga, the karana, and, when you give the child's birth star, Tara Bala and Chandra Bala. At the window level it computes Rahu Kaal, Yamaganda and Gulika Kaal from your city's real sunrise and sunset and drops any candidate that overlaps them, along with any window touching a tithi-gandanta band.
It does not check Guru or Shukra asta on this page. The combustion check runs only on the rites whose own source calls for it - marriage, Griha Pravesh, Upanayana, Karnavedha and a few others - and the Mundan row is not among them, so an asta day here is neither flagged nor scored down. It does not check Adhik Maas either: the finder scores one civil day at a time and has no month-level rule, so an intercalary month has to be checked separately. The almanac panel on the Panchang page names the current lunar month and whether it is adhika.
For educational purposes. Astrological interpretations are traditional and not a substitute for professional advice.