Understanding Nepali Patro: The Official Bikram Sambat Calendar of Nepal
The Nepali Patro (नेपाली पात्रो) is the official astronomical and civil calendar of Nepal, established upon the Bikram Sambat (BS) solar framework alongside classical Vedic lunar Panchanga. Officially adopted as the national civil calendar under King Rana Bahadur Shah and formalized by the Government of Nepal, it governs all national holidays, school and fiscal years, gazetted notices, and religious festivals.
How Does Bikram Sambat (BS) Work in Nepal?
Unlike the lunar calendar where months are defined by Moon phases (Tithis), the civil months of Bikram Sambat in Nepal are solar months (Sankranti-based):
- Solar Gate (गते): The day of the month is called Gate. The month begins on the day of the Sun's transit (Sankranti) into a new zodiac sign. Because the Earth's orbit is elliptical, Nepali months vary between 29 and 32 days in length.
- The 12 Nepali Months: Baisakh, Jestha, Asar, Shrawan, Bhadra, Ashwin (Asoj), Kartik, Mangsir, Poush, Magh, Falgun, and Chaitra.
- New Year (Naya Barsha): Celebrated on Baisakh 1 (Mesha Sankranti, typically April 13 or 14), heralding the arrival of spring and harvest festivities like Bisket Jatra in Bhaktapur.
The Integration of Lunar Tithis in Nepali Culture
While administrative and legal affairs follow solar Gate, all sacred Nepali festivals are governed by lunar Tithis:
- Bada Dashain (बडा दशैं): The greatest festival of Nepal, celebrated from Ashwin Shukla Pratipada (Ghatasthapana) through Phulpati, Maha Ashtami, Maha Navami, and Bijaya Dashami (Tika and Jamara).
- Tihar (तिहार / Yamapanchak): The five-day festival of lights, worshiping Kaag (Crow), Kukur (Dog), Gai (Cow), Laxmi Puja, Gobardhan Puja / Mha Puja, and culminating in Bhai Tika.
- Chhath Parva: The sacred worship of Surya and Chhathi Maiya observed on Kartik Shukla Shashthi in the Terai and across rivers nationwide.
- Haritalika Teej & Rishi Panchami: The grand fast of women dedicated to Lord Shiva and Goddess Parvati in the month of Bhadra.
Semi-Technical Mechanics: Local Time (NPT) and Ephemeris Alignment
Nepal Standard Time (NPT) is unique globally as it is calibrated to the 86° 15′ East meridian passing through Mount Gauri Sankar, creating an exact offset of UTC+5:45 (15 minutes ahead of Indian Standard Time). This engine computes high-precision solar elevations, sunrise, sunset, and micro-tithi boundaries referenced directly to local terrestrial coordinates across the Kathmandu Valley and the Himalayan regions.
Decades of Precision
Proprietary astronomical engine active since 2004 computing exact Bikram Sambat solar gates and Nepali Tithi boundaries.
100% Privacy
Calculations run in encrypted memory sessions and are never stored or shared.
National Authenticity
Engineered strictly under Nepal Panchanga Nirnayak Samiti standards and classical Drik-Siddhantic astronomical canons.