Here is a simple, Jain-dharmic outline of how a Jain panchang is calculated, with emphasis on the traditional elements used in the calendar for rituals, fasts, and Auspicious days.

What panchang includes

• Tithi (lunar day): The count of lunar days in a month. It marks auspicious or inauspicious timings for vows, fasts, and pujas.
• Vara (weekday): The day of the week, which influences which fasting or vrata are observed.
• Nakshatra (constellation): The stellar mansion in which the Moon resides; certain nakshatras are considered auspicious for specific rites.
• Yoga: A particular combination of Sun and Moon positions that is considered for auspiciousness or inauspiciousness.
• Karan: Half of a tithi; another factor used to determine the timing of rituals and fasts.

Key ideas behind the calculation

• Based on celestial positions: The panchang uses the positions of the Sun, Moon, and sometimes other planets to determine tithi, nakshatra, yoga, and karan.
• Lunar-solar framework: Months are aligned with the phases of the Moon, but social and religious observances are tied to solar timings (sunrise/sunset) for daily activities, ceremonies, and vrat.
• Start and end rules: Each tithi, nakshatra, yoga, and karan has a defined start and end moment, usually defined in relation to sunrise or a particular longitudinal motion, so a single day can contain multiple panchang events (e.g., a tithi changing during the day).

Differences that may appear between Digambar and Shwetambar communities

• Some observances or the names of certain days may differ slightly, or the emphasis on certain tithis and fasts may vary.
• The core mechanics—tithi, vara, nakshatra, yoga, karan—remain the same, but regional or sect-specific traditions can affect how strictly certain days are observed or which days are considered especially auspicious.

How it’s used in practice

• Auspicious days for temple ceremonies, festival timings, and personal vows are chosen based on favorable combinations in the panchang.
• Fastings and vrata often align with certain tithis or nakshatras.
• Daily routines and temple rituals may be guided by the panchang, especially in the preparation of major Jain festivals and pilgrimages.

Simple step-by-step view 1) Determine tithi: Find the lunar day count from new moon to the following new moon (or from full moon to the next, depending on local convention). This tells you which days are suitable for fasting or rituals. 2) Determine vara: Identify the weekday of the day in question. 3) Determine nakshatra: Look at which lunar mansion the Moon is in at that time. 4) Determine yoga and karan: Compute the Sun–Moon geometry to find the associated yoga and karan. 5) Combine: Use all five elements to decide observances for the day (which fasts, pujas, or auspicious activities to undertake, and which days to avoid for certain ceremonies).

If you’d like, I can summarize a specific Jain panchang for a given date (with absolute dates), or explain how a particular panchang tradition (Digambar vs. Shwetambar) applies to a festival or fast.