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.
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.
Mundan is traditionally performed in an odd year of the child's life - most often the first, third or fifth year. Some families do it earlier at their kula temple, but the odd-year rule and avoiding the birth month are the common guidelines.
Classical astrology favours months when the Sun is in Uttarayana and the Moon is waxing, broadly from Magha through Jyeshtha. The child's own birth month and birth nakshatra are usually avoided, so the exact dates depend on the horoscope. These are year-level rules you apply when choosing the range to search, since the finder scores single days.
Tradition says yes: like other Hindu samskaras, Mundan is not performed when Jupiter (Guru) or Venus (Shukra) is combust, during Adhik Maas, or on Rikta tithis. This calculator checks the Rikta tithis and marks them down, but it does NOT run the Guru/Shukra asta check on the Mundan page - that check applies only to the rites whose own source calls for it, such as marriage and Griha Pravesh. It does not check Adhik Maas either, because it scores one civil day at a time and has no month-level rule. Check both separately; the Graha Asta page gives the combustion periods and the Panchang page names the current lunar month.
Twelve: Ashwini, Mrigashira, Punarvasu, Pushya, Hasta, Chitra, Swati, Jyeshtha, Shravana, Dhanishta, Shatabhisha and Revati. A day whose Moon falls in one of these gains points; a Ganda Moola junction nakshatra loses them. The set differs from the one used for a naming ceremony or a marriage in the same finder.
No, it is optional. Without it the finder ranks days on the tithi, nakshatra, vara, yoga and karana alone. Adding the child's Janma nakshatra lets it also weigh Tara Bala and Chandra Bala, so the day suits the child personally rather than only being generally clear.
For educational purposes. Astrological interpretations are traditional and not a substitute for professional advice.