About and How We Calculate

Panchang USA is a free Hindu calendar for people who live in the USA and want the Vikram Samvat Panchang beside the Gregorian date, for their own city, with every time given exactly.

What the site calculates

For any date and city we calculate the five limbs of the Panchang with their exact start and end times: tithi (lunar day), vara (weekday), nakshatra (lunar mansion), yoga and karana. We also calculate sunrise, sunset, moonrise and moonset, Rahu Kalam, Yamaganda, Gulika Kalam, Abhijit Muhurat, Brahma Muhurta and Choghadiya, the Hindu month and paksha, the Vikram Samvat and Shaka years, the dates of festivals and vrats, eclipses, and auspicious days for common occasions.

The method

• Positions. The Sun and the Moon are placed with the open-source Astronomy Engine library, which agrees with the Swiss Ephemeris, the reference used by professional Panchang software, to within a few arcseconds.
• Zodiac. The sidereal zodiac with the Lahiri (Chitrapaksha) ayanamsa, the standard in India.
• The Hindu day. A day runs from sunrise to the next sunrise, and the tithi at sunrise (the udaya tithi) names the day. Because a tithi can begin or end at any hour, we always show its exact start and end.
• Months. Both the Purnimanta (North Indian) and Amanta (Gujarat, Maharashtra, South India) names are shown. Adhika (extra) months are detected from the sun’s movement, not from a table.
• Sunrise and sunset. The upper edge of the Sun at the horizon, with standard refraction. Moonrise and moonset use the centre of the Moon’s disc, the usual Panchang convention.
• Festival days. Each festival is tied to a tithi and to a part of the day (sunrise, midday, the evening twilight called Pradosh, midnight, moonrise and so on) according to the Dharmashastra rules that panchang-makers follow.

How the results were checked

Before publication the calculations were compared with independent sources:

• About 3,700 tithi, karana, nakshatra and yoga boundaries in 2026 and 2027 were compared with the Swiss Ephemeris: every one fell within about 20 seconds.
• Daily values for Chicago (sunrise, moonrise, tithi, nakshatra, yoga and karana end times, Rahu Kalam, Abhijit Muhurat, the month and the Samvat years) were compared with a published online Panchang: 96 of 99 values matched to the minute, and the remaining three were within seconds of a rounding boundary.
• More than 220 festival, Ekadashi, Purnima, Sankranti and vrat dates for 2026 and 2027 were compared with the same published calendar for Chicago, and all matched except one festival that the published calendar places in an Adhika month (Ganga Dussehra 2026). We keep the classical rule and show the regular Jyeshtha.

The written guides were checked by independent reviewers against published sources, and every page says where traditions differ. Where something could not be verified we left it out.

Limits you should know about

• Printed Panchangs and other websites may differ from ours by a minute, and occasionally by a day for a festival, because there are several valid rules and local traditions. When in doubt, follow your family’s tradition and your priest.
• Muhurat dates follow general classical rules. A personal muhurat is made from your family’s horoscopes by a qualified jyotishi.
• Times are for the city you choose (its latitude, longitude and time zone, with daylight saving applied automatically).

Credits

Astronomical positions: Astronomy Engine by Don Cross (MIT licence). Accuracy checks: Swiss Ephemeris. City names, coordinates and time zones: GeoNames (CC BY 4.0).

Contact

Corrections and suggestions are welcome: [email protected].