Rasi & Nakshatra Calculator

What is a Rasi and Nakshatra Calculator?

In Vedic astrology, Rasi usually refers to the zodiac sign occupied by a particular planet. When people ask for their Janma Rasi (birth Rasi), they commonly mean the Chandra Rasi — the sidereal Moon sign at the birth moment. Janma Nakshatra is the lunar mansion occupied by the Moon at that same time; this is also called a birth star.

The Moon moves through the zodiac much faster than the Sun. That is why a simple date-only sun-sign rule cannot reliably find a Vedic birth star. Two babies born on the same date but at different times can have different Nakshatra Padas, and sometimes different Nakshatras or Rasi.

CalcuPortal's calculator estimates the Moon's position using Astronomy Engine's astronomical lunar model and a Lahiri-style approximate sidereal conversion. The output is intended for cultural interest. It does not represent the exact Swiss Ephemeris Lahiri implementation or a Panchang-certified birth chart.

How to Find Rasi and Nakshatra from Your Date of Birth

1. Enter birth date: choose year, month and day exactly as recorded.
2. Enter birth time: choose the recorded clock time, not a guessed default. If unavailable, uncheck “I know my birth time.”
3. Choose the birthplace time zone: for Indian birthplaces, select IST / Asia/Kolkata; for places with daylight saving, use the correct historical time-zone location.
4. Calculate the Moon longitude: the browser converts local time into UTC and estimates the Moon's position along the tropical ecliptic.
5. Convert to sidereal: subtract the approximate Lahiri ayanamsa from the tropical Moon longitude, adjusting into 0°–360°.
6. Find the lunar sectors: divide by 30° for Rasi, 13°20′ for Nakshatra and 3°20′ for Pada.
7. Check uncertainty: if birth time is unknown, review every possible sector across the full local date, plus approximate changeover times.

Rasi / Nakshatra formula

As a transparent mathematical example, a hypothetical sidereal Moon longitude of 48° falls in Vrishabha Rasi (30°–60°). It is inside Rohini Nakshatra (40°–53°20′), at 8° within the Nakshatra, making it Rohini Pada 3. This is a worked sector example, not a result for a particular birthday.

12 Rasi Names in English and Tamil

The 12 Vedic Rasi divide the sidereal zodiac into equal 30° signs. Tamil horoscope calendars often use these native names when describing a person's Janma Rasi.

27 Nakshatras with Tamil Names and Ruling Planets

Every Nakshatra covers 13°20′ (one twenty-seventh of the zodiac) and is traditionally associated with a ruling planet in the Vimshottari sequence. The table below lists the 27 birth stars and their familiar Tamil names. Standard spellings may vary by language and transliteration.

The spans are displayed as approximate decimal degrees for compact reference; the true sector definition is exactly 360°/27 = 13°20′ per Nakshatra. The ruling-planet sequence repeats every nine Nakshatras: Ketu, Venus, Sun, Moon, Mars, Rahu, Jupiter, Saturn and Mercury.

What Is Nakshatra Pada? Meaning of Pada 1, 2, 3 and 4

Each of the 27 Nakshatras contains four equal quarters known as Padas, giving a total of 108 lunar quarters around the full zodiac. Since each Nakshatra covers 13°20′, one Pada covers exactly 3°20′.

Nakshatra Padas are smaller than full Nakshatras, so they can change several times during one calendar day. A result near a Pada boundary is especially sensitive to the recorded birth time and the ayanamsa/ephemeris convention.

Tamil Rasi Nakshatra Calculator: Tamil Birth Star Finder

People often search for “Rasi Nakshatra calculator Tamil” or “Rasi Nakshatra by date of birth in Tamil” to find their ராசி (Rasi), நட்சத்திரம் (Nakshatra) and பாதம் (Pada). CalcuPortal displays the traditional Tamil labels alongside English spellings for each result.

For example, Mesha is மேஷம், Vrishabha is ரிஷபம் and Karka is கடகம்; Rohini is ரோகிணி, Chitra is சித்திரை and Revati is ரேவதி. The 27-Nakshatra table above lists all Tamil names.

If you were born in Chennai, Bengaluru, Coimbatore, Madurai, Hyderabad, Mumbai or Delhi, the standard modern India time zone is Asia/Kolkata (IST). Historical records from before today's standardisation may require care; the tool uses IANA historical time-zone rules for the chosen location. It does not guess your city's exact birth-time offset from an IP address.

Can You Find Nakshatra Without Birth Time?

A date-only Rasi Nakshatra calculator may sometimes show one possible Nakshatra throughout a local date. But the Moon often moves about one Nakshatra per day, so the birth star or Pada may change during the day. Assigning one definite answer at noon when the actual birth time is unknown can be misleading.

For that reason, unchecking “I know my birth time” makes this tool examine the full local calendar day, reporting every Nakshatra/Pada combination encountered and the approximate times of transitions. It does not silently substitute a midnight or noon birthday.

Where a change occurs near midnight or you are within a small angular distance of a boundary, a professionally calculated Panchang with precise birth records is best. Even when the tool finds only one star across the day, a different sidereal convention can alter a result near a boundary.

Why Birthplace, Birth Time and Ayanamsa Matter

The local clock time must be converted to UTC before calculating the Moon's position. A birth at 6:00 AM in Chennai and a birth at 6:00 AM in New York are two different astronomical moments. Daylight-saving changes can cause some local clock times to be skipped or repeated, so a place-aware time-zone database is more useful than assuming a modern fixed offset for every historical date.

The Moon position in this calculator is geocentric, meaning measured relative to Earth's centre, as is common in Vedic sign and Nakshatra calculations. Therefore the birthplace's latitude and longitude are not needed to derive the geocentric ecliptic longitude, but the birth location still matters for interpreting the recorded time. Other astrological outputs such as Lagna (Ascendant) require geographical coordinates and a different calculation.

What is Lahiri ayanamsa?

Ayanamsa is the angular offset used to convert from tropical to sidereal longitude. A commonly used Vedic convention is Lahiri (Chitrapaksha), around 24°13′ in 2026. This implementation uses an approximate Lahiri-style value derived from a J2000 precession formula, rather than reproducing the precise Swiss Ephemeris Lahiri mode with all nutation and model adjustments. This means that near a sign, Nakshatra or Pada boundary, a specialised chart can disagree.

The Moon is calculated from Astronomy Engine's geocentric lunar position (EclipticGeoMoon), a published mathematical astronomy library, and then the approximate sidereal offset is subtracted. For the background of the sidereal framework, see Swiss Ephemeris documentation on Lahiri ayanamsa. These sources explain the method; they do not certify this tool as equivalent to Swiss Ephemeris.

Rasi vs Nakshatra vs Western Zodiac Sign vs Lagna

Lagna (Ascendant) is a fourth concept: the zodiacal point rising at the eastern horizon at a specific time and place. Unlike the geocentric Rasi calculation here, Lagna needs coordinates and local sidereal-time geometry. Do not treat any of these four quantities as interchangeable.

Common Rasi and Nakshatra Calculation Mistakes

• Using a Sun-sign birth-date table: a Vedic Janma Rasi uses the Moon, not a fixed Western Sun-sign date range.
• Ignoring the recorded time zone: even a correct birth date can give a different lunar position if UTC conversion is wrong.
• Assuming time is unnecessary for the Pada: a Nakshatra Pada can change within a few hours.
• Mixing sidereal conventions: Lahiri, Raman and other ayanamsas do not always assign the same boundary result.
• Using the modern offset for every past year: many locations have historical daylight-saving rules.
• Confusing birth Rasi with Lagna: the Moon sign and ascendant are computed differently.
• Believing every result is exact: this page uses an approximate Lahiri model; verify close boundaries independently.
• Treating astrology as scientific prediction: an astronomical Moon position does not establish someone's character, health or future events.

Rasi Nakshatra Calculator: Frequently Asked Questions

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