Show the math.

The engine

Bela is a precision instrument for sacred timing, not a content farm. The same input always produces the same answer, and the answer carries its reasoning with it.

• Ephemeris: Swiss Ephemeris (full DE-series files; never the Moshier fallback), verified at process start.
• Ayanamsa: Lahiri (Chitrapaksha), frozen process-wide; mean Rahu/Ketu, per classical practice.
• Ganit: drik ganit — tithi, nakshatra, yoga and karana from true solar/lunar longitudes; sunrise/sunset with disc-centre + refraction.
• Panchang convention: the day's limbs are evaluated at the local sunrise instant, the classical rule.
• Reference city: national lists are computed for Delhi (IST, 28.61°N 77.21°E); city panchang pages recompute per location.

How a muhurat date is chosen

For each activity the engine scans every choghadiya window of the year (16 per day) and scores it by documented classical rules:

1. Gates. A window is disqualified if it overlaps Rahu Kaal, Yamaganda, Gulika, Durmuhurtam or a bad Panchaka (Mrityu, Agni, Raja, Chora, Roga).
2. Weights. Amrit/Shubh choghadiyas, activity-suited nakshatras (Saptadha classification), non-rikta tithis, benign yogas and the Abhijit Muhurat add strength; harsher combinations subtract.
3. Inclusion. A date is listed only if its best window clears the gates, the nakshatra suits the activity, the tithi is not rikta/Amavasya, and the yoga is not Vyatipata or Vaidhriti.
4. Prohibitions. For marriage and griha pravesh, dates inside Chaturmas, Kharmas (Malmas) and Adhik Maasa are excluded, as in traditional panchang lists.

The published 0–100 score is a fixed, public mapping of the engine's internal score: score = clamp(round((engine_score + 40) × 100 / 95), 0, 100). 70+ reads as auspicious, 40–69 moderate, below 40 avoid. Every date on the muhurat pages shows the full ✓/✕/~ breakdown — that breakdown is the product, not decoration.

What is modelled — and what is not (yet)

Trust comes from stating the boundary. Here is the honest scope of the current engine:

No generic list — ours included — can apply Tara Bala or Chandra Bala, which judge the day's Moon against your birth star. That needs a chart; the Bela app applies both, per family member, to every window.

No LLM, no fabricated prose, no data leaving the process

Large language models are eloquent and frequently wrong about ephemeris arithmetic. So the pipeline is strict: dates, windows, tithis and scores come only from the engine; the prose around them is authored to describe those computed facts, never to invent new ones. Site JSON is regenerated deterministically — no wall-clock stamps inside the data, and the same engine version reproduces the same files byte-for-byte.

Privacy follows the same discipline. Computation runs on a vendored, hash-pinned engine (PyJHora-class, v4.8.7, audited) — fully offline, no network calls. In the app, birth details are computed on-device and never uploaded; we cannot leak or sell data we never receive.

Classical sources

The rule set is drawn from the standard muhurta literature rather than invented: the Muhurta Chintamani of Rama Daivajna (the reference for Rahu Kaal, Panchaka-rahita, tithi and nakshatra fitness and the prohibited periods), the Kalaprakasika (the South-Indian muhurta tradition, including choghadiya practice), and the electional chapters of Varahamihira's Brihat Samhita. The Saptadha nakshatra classification and the Abhijit Muhurat follow these authorities as reflected in living panchang practice.

Where traditions differ — Smarta vs Vaishnava Ekadashi, regional calendars, Holi's Bhadra split — we follow the popular North-Indian convention for Delhi and say so on the page. Computed festival dates are cross-checked against widely used calendars each regeneration.

Verify us

The same data this site renders is downloadable — CSV and JSON, CC-BY — on the datasets page, with the per-rule breakdown included. If you find a date that fails a rule we claim it passes, that is a bug we want to hear about.