How we calculate the Panchang
Every date and time on Kreotek Calendar is computed from astronomy, then checked against Drik Panchang, India's most widely used online panchang. Here is exactly how — and how accurate it is.
Accuracy, measured
- Festival & vrat dates checked against Drik Panchang (2019 sample, 2025, 2026, 2027)
- 424 / 424 match
- Daily Panchang values checked (sunrise, tithi, nakshatra, yoga, karana, Rahu Kalam, Varjyam…)
- within the printed minute; 5 cases differ by 1 minute
- Festival timings checked (muhurat, parana, tithi begin/end)
- 18 of 22 exact, 4 within 1 minute
- Sunrise / sunset and moonrise / moonset (New Delhi, 5 days)
- 10 / 10 and 10 / 10 exact
Astronomy: Drik Ganita
We use modern, observation-based astronomy (Drik Ganita), not the older Surya Siddhanta tables. The Moon's position comes from the ELP/MPP02 lunar theory fitted to NASA's DE405 ephemeris and the Sun's from VSOP87 — both accurate to about a second of arc. Positions are converted to the sidereal zodiac with the Lahiri ayanamsa.
Tithi is the Moon–Sun angle in steps of 12°, nakshatra is the Moon's sidereal position in steps of 13°20′, yoga is the sum of the two, and karana is half a tithi. Each one is located to the second, so we can show exactly when it ends.
Sunrise, the Hindu day and muhurat
The Hindu day runs from sunrise to the next sunrise, and the tithi “of the day” is the one at sunrise. Rahu Kalam, Yamaganda and Gulika divide daytime into eight parts; muhurtas divide day and night into fifteen; Choghadiya and Hora follow their traditional weekday sequences. All of these depend on your city, so we recompute them for the place you choose.
Festival rules
Each festival is a tithi in a Hindu month plus the time of day when that tithi must prevail (sunrise, purvahna, madhyahna, aparahna, pradosh, nishita or moonrise), with the classical exceptions: Bhadra for Raksha Bandhan and Holika Dahan, Rohini nakshatra for Janmashtami, Shravana nakshatra for Dussehra, Dwadashi for Ekadashi parana, and the Adhik Maas rules. Ekadashi shows both the Smarta date and, where it differs, the Gauna (Vaishnava) date.
Eclipses and Sutak
Eclipse contacts are computed for your location, and an eclipse is only observed — with Sutak — where it is actually visible: 9 hours before a lunar eclipse and 12 hours before a solar eclipse, ending with the eclipse.
Known limits
- Times are rounded to the minute; near a boundary our minute can differ from another panchang's by one.
- Regional calendars (Tamil, Bengali, Malayalam, Odia solar months) and regional festival variants are being added.
- Elevation is not included (sea-level sunrise), matching Drik Panchang's default.
Data and credits
City coordinates and time zones: GeoNames (CC BY 4.0). Astronomy libraries: astronomia and Astronomy Engine (MIT).
Frequently asked questions
Why does a festival date sometimes differ between calendars?
A festival is kept on the day its tithi is present at a particular time — sunrise for most, midday for Rama Navami, midnight for Janmashtami, moonrise for Karwa Chauth. When a tithi starts or ends close to that moment, two places (or two panchangs using different rules) can land on different days. We follow the rules Drik Panchang uses and calculate for your city.
Which ayanamsa do you use?
Lahiri (Chitrapaksha), the ayanamsa adopted by the Government of India's Calendar Reform Committee and used by Drik Panchang.
How is sunrise defined?
When the upper edge of the Sun appears on the horizon, with standard atmospheric refraction, at sea level — the same definition Drik Panchang uses by default.
Is my data sent anywhere?
No. All Panchang calculations run in your browser, your events are stored only on your device, and the city search runs on a list downloaded to your device. There are no ads and no sign-up.