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Tithi Birthday Calculator | Lunar Anniversary Dates

The Tithi Birthday Calculator computes the tithi at birth (the Moon−Sun elongation band) and then finds the civil dates each year when that tithi recurs at the same paksha — the lunar birthday used for annual rites, puja anniversaries and griha events that follow tithi rather than the solar date.

Last updated: September 2026 · Free · No sign-up required

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Results

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Quick reference

Tithi list (each paksha): Pratipada, Dwitiya, Tritiya, Chaturthi, Panchami, Shashthi, Saptami, Ashtami, Navami, Dashami, Ekadashi, Dwadashi, Trayodashi, Chaturdashi, Purnima/Amavasya.

public Location matters

Tithi and nakshatra boundaries depend on where you are — enter your city's coordinates for precise results.

schedule Ayanamsa

Calculations use the Lahiri (Chitrapaksha) ayanamsa, the standard for Vedic charts.

menu_book Panchang basis

Results follow drik-panchang style astronomical computation, not printed-table approximation.

school Traditions differ

Some regions use Surya Siddhanta conventions; where traditions conflict, your family panchang wins.

lightbulb A real example — from elongation to Dashami

A user's birth record notes the Moon stood 115° ahead of the Sun at birth. They want their lunar birthday and its 2026 recurrence.

Result: 115° ÷ 12° = 9.58, so the tithi is the 10th — Dashami; since 115° is under 180°, it is Shukla Dashami (bright fortnight). Each tithi spans 12° of elongation and the Moon gains about 12.19° per day on the Sun, so a tithi lasts roughly 23.6 hours — the calculator reports the tithi's exact local window (start and end times), which matters more than the civil date for timing rites.

What this means: The 2026 recurrence lands on a different civil date than the solar birthday because the lunar year (354.37 days) runs about 10.88 days short of the solar year — the gap accumulates roughly a month every three years. In some years the tithi occurs twice or not at all; the calculator lists every occurrence with its window instead of forcing a single date.

Formula & methodology

Formula: Tithi = ⌊(Moon−Sun elongation) ÷ 12°⌋; Nakshatra = ⌊Moon longitude ÷ 13°20'⌋; Vimshottari lord sequence Ketu→Venus→Sun→Moon→Mars→Rahu→Jupiter→Saturn→Mercury

How the lunar birthday is found

The birth tithi comes straight from the Moon–Sun elongation at birth: floor(elongation ÷ 12°) + 1 gives the tithi number (1–15 Shukla, then 1–15 Krishna), so 115° means Shukla Dashami. The paksha follows from the elongation itself: under 180° is the bright fortnight, over it the dark.

For each target year, the calculator scans the ephemeris for recurrences of that same tithi and paksha and reports every occurrence with its local start and end times. Boundary handling is explicit: because a tithi averages about 23.6 hours, each recurrence is assigned to the civil date carrying it at local sunrise, and years where the tithi is skipped or doubled — the 354-day lunar year drifting against the 365-day solar year — are shown as-is rather than rounded to a single date.

Frequently asked questions

What is a birth tithi?
The lunar day you were born — one of 15 Shukla or 15 Krishna tithis defined by the Moon's angular distance from the Sun in 12° steps.
Why does the lunar birthday differ from the calendar birthday?
Tithis average about 0.98 days and shift against the solar calendar, so the tithi recurs on a different civil date each year.
Which events use tithi birthdays?
Annual shraddha rites, many temple festival anniversaries, and family puja days traditionally follow tithi, not the solar date.
Can a tithi birthday occur twice in a year?
Yes — because the lunar year (354 days) is shorter, some years show the tithi twice and others miss it; the calculator lists exact occurrences.

Explore the full Hindu & Vedic toolkit

Every CalcaTools Hindu calculator — kundali and birth charts, planetary dashas, doshas and remedies, panchang and muhurat timings, festival dates, and vastu — computed with the same Lahiri-ayanamsa astronomy engine validated against published ephemerides.

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