Frequently asked questions

Questions and answers

What is fatcalendar?

fatcalendar.com is a free, ad-free calendar that shows the same day in many traditions - Gregorian, Telugu, Tamil, Kannada, Malayalam, Marathi, Gujarati, Punjabi, Bengali, North-Indian (Hindi), Indian-Muslim (Hijri) and Christian - in any of eleven languages, with tithi, nakshatra, festivals, auspicious windows and prayer times calculated for your location.

Is tradition the same as language?

No. Tradition decides how time is reckoned (which months, eras, festivals and rules apply); language only decides how it is displayed. You can read the Tamil calendar in English or the Hijri calendar in Telugu.

Where does the astronomical data come from?

All astronomy (sunrise, sunset, tithi, nakshatra, yoga, karana, lunar months, planetary ingresses) comes from the jotish.ai ephemeris API. fatcalendar applies published rule arithmetic on top of it (for example Choghadiya, Durmuhurtham, Varjyam, solar-calendar dates and festival rules). A few items jotish cannot supply - Easter computus, fixed Nanakshahi arithmetic, tabular Hijri fallback and prayer-time twilight geometry - are computed locally.

Are the results accurate?

Astronomical positions are precise; the cultural rules that pick a festival date can differ between almanacs (panchangams), regions and sects, so a festival may be observed a day apart in different places. Hijri month starts depend on local moon sighting: fatcalendar marks Hijri dates as provisional. For religious observance, confirm with your local authority.

How is my location used?

Tithi end times, sunrise and Rahu Kalam depend on where you are. If you allow it, your browser location (or the approximate location Cloudflare derives from your IP) is used only to compute the calendar, rounded to 0.1 degrees. We do not store it against you and we have no accounts.

Do you use cookies or tracking?

No tracking cookies and no advertising. Your tradition, language and place preferences are kept in your browser localStorage only. See the privacy page.

Is there an API?

Yes, a free, key-less REST API (OpenAPI 3.1 at /openapi.json), an MCP server at /mcp for AI assistants, an A2A agent at /a2a and a TypeScript SDK. The limit is 120 requests per 60 seconds per client.

How do I connect fatcalendar to Claude, Cursor or another AI assistant?

Add the remote MCP server https://fatcalendar.com/mcp (Streamable HTTP, no authentication). See /docs/mcp for ready-to-paste configuration.

Are results cached?

Yes. Astronomical results never change, so each calculation is computed once and cached permanently; repeated requests are served from cache.

How do I cite fatcalendar?

Cite as: fatcalendar.com - multi-tradition calendar and panchang (data: jotish.ai ephemeris). Link to https://fatcalendar.com and mention the date retrieved.