Use the Panchang Tithi Calculator to estimate the Hindu lunar day for a selected date, time, and UTC offset. Explore Shukla Paksha, Krishna Paksha, lunar angles, approximate tithi transitions, and the astronomical principles behind the traditional Panchang.
Enter a date, local clock time, and UTC offset to estimate the tithi occurring at that instant. The result includes approximate transition times.
In the Hindu calendar, a tithi is determined by the angular separation between the Moon and Sun along the ecliptic. Each tithi occupies 12 degrees of increasing lunar elongation, producing 30 tithis during a complete synodic lunar cycle.
Unlike a conventional civil day, a tithi does not necessarily begin at midnight or last exactly 24 hours. The Sun and Moon move at changing apparent speeds, so the beginning and ending times shift throughout the month.
This Panchang Tithi Calculator uses an approximate geocentric astronomical model. It estimates the lunar day at your chosen instant rather than assigning a single tithi to an entire calendar date.
For related astronomical comparisons, explore the Moon Phase Calculator, Full Moon Calendar, and Vedic Birth Chart Calculator.
For religious observances, sunrise-based calendar rules, or precise muhurta selection, consult a location-specific traditional Panchang prepared with a validated ephemeris.
Select the local date and time. Choose the UTC offset that applies to your location on that date, including daylight saving time where relevant.
Times are approximate and use the selected fixed UTC offset. The calculation does not determine sunrise, festival observance, or the complete five-part Panchang.
Enter geocentric ecliptic longitudes in degrees. Use both longitudes from the same instant and reference frame.
Longitude values alone cannot establish the beginning or ending clock times. Those require time-dependent planetary positions.
A tithi is a fundamental unit of the traditional Hindu lunisolar calendar. Its definition depends on the angular relationship between the Sun and Moon, rather than the passage of a fixed number of hours. The lunar month is divided into 30 tithis, each representing 12 degrees of relative angular movement.
The first 15 tithis belong to Shukla Paksha, the waxing fortnight, which progresses toward the full moon. The next 15 belong to Krishna Paksha, the waning fortnight, which progresses toward the new moon. These divisions form the basis for many traditional calendar dates and religious observances.
The Panchang Tithi Calculator helps identify the astronomical tithi at a specific moment. However, a calendar day in a traditional Panchang is frequently associated with the tithi prevailing at local sunrise. These are related but different questions, and their answers can differ on the same civil date.
Traditional calendars also account for regional practices, festival-specific rules, and astronomical conventions. For example, a festival may depend on a tithi occurring during a particular part of the day or night rather than simply at sunrise.
Understanding these distinctions makes the result more useful. A computed tithi is an astronomical classification, while its religious or cultural application requires additional context.
Learn how lunar days fit into the broader system of traditional Indian calendrical astronomy.
A tithi measures 12 degrees of increasing angular separation between the Moon and Sun. Because the Moon travels around Earth much faster than the Sun appears to move along the ecliptic, this angular difference increases through the lunar month.
The Panchang Tithi Calculator determines which 12-degree interval contains the selected moment. For example, a separation of 27 degrees falls within the third tithi, Tritiya. A separation of 190 degrees falls within the first tithi of Krishna Paksha, following the full-moon boundary.
Tithi duration is variable. A lunar day can begin during the morning, afternoon, evening, or night, and its ending time may fall on a different civil date. This is why date-only shortcuts cannot reliably establish the tithi at every hour.
Vara refers to the weekday within the traditional Panchang. The seven days are associated with the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. The names include Ravivara, Somavara, Mangalavara, Budhavara, Guruvara, Shukravara, and Shanivara.
In traditional sunrise-based reckoning, the weekday may be considered from one local sunrise to the next. This differs from the conventional midnight-to-midnight civil calendar. Consequently, a clock time before sunrise may belong to a different traditional day designation than its civil weekday suggests.
Vara is a separate calendar component. It cannot be calculated from the Sun–Moon elongation alone and is not included in the lunar-angle result.
Nakshatra divides the sidereal zodiac into 27 equal sectors of 13 degrees and 20 arcminutes each. The Moon's sidereal longitude determines which nakshatra it occupies at a particular moment. Familiar names include Ashwini, Bharani, Krittika, Rohini, Mrigashira, and Pushya.
Unlike tithi, which depends on the difference between solar and lunar longitude, nakshatra depends on the Moon's position relative to a sidereal zodiac. A chosen ayanamsa is therefore important for a consistent nakshatra calculation.
A person can experience a nakshatra change without a simultaneous tithi change. Both elements provide distinct information within the Panchang.
Nitya Yoga is calculated using the sum of the sidereal longitudes of the Sun and Moon. The complete circle is divided into 27 equal segments, each measuring 13 degrees and 20 arcminutes.
Traditional yoga names include Vishkambha, Priti, Ayushman, Saubhagya, and Shobhana. These classifications have conventional interpretations in Hindu calendrical and astrological practice.
Yoga must not be confused with tithi. One calculation uses a sum of longitudes, while the other uses their difference. Both require consistent celestial coordinates, but they describe different astronomical relationships.
A karana represents half a tithi, corresponding to six degrees of increasing Sun–Moon elongation. Therefore, two successive karana intervals make one complete tithi. The lunar month contains 60 karana occurrences distributed among 11 traditional karana names.
Seven names repeat cyclically: Bava, Balava, Kaulava, Taitila, Gara, Vanija, and Vishti. Four fixed karanas—Shakuni, Chatushpada, Naga, and Kimstughna—occur at specified positions in the lunar cycle.
Karana boundaries occur more frequently than tithi boundaries. A result that identifies the tithi does not automatically establish the karana unless the six-degree interval is also calculated.
The calculation begins with the geocentric ecliptic longitudes of the Sun and Moon at a selected instant. The lunar longitude is subtracted from the solar longitude in the appropriate order: Moon minus Sun. The resulting angle is normalized into the range from 0 degrees up to, but not including, 360 degrees.
The fundamental relationship is:
E = (Moon Longitude − Sun Longitude + 360°) mod 360°
Tithi IndexTithi = floor(E ÷ 12°) + 1
The resulting index ranges from 1 to 30. Values 1–15 belong to Shukla Paksha; values 16–30 belong to Krishna Paksha.
For a numerical example, suppose the Sun has an ecliptic longitude of 100 degrees and the Moon has a longitude of 136 degrees. Their elongation is 36 degrees. Dividing 36 by 12 gives 3, so the tithi index is 4, corresponding to Shukla Chaturthi.
Notice that the interval begins at the boundary. An elongation of exactly 36 degrees is already in the fourth tithi, not the third. The same boundary convention applies throughout the lunar month.
The Moon's orbital speed varies because its orbit is elliptical and is affected by gravitational perturbations. The apparent motion of the Sun also varies slightly throughout the year. Consequently, the difference between their longitudes does not increase at a perfectly constant rate.
The date-and-time mode uses a compact approximate solar and lunar position model. It searches backward and forward from the selected instant to estimate when the elongation crosses the relevant 12-degree boundaries. A numerical refinement then produces approximate start and end times.
These estimates are not equivalent to a high-precision astronomical ephemeris. The model omits some smaller periodic terms and does not include all corrections used in professional Panchang production. Results should be treated as educational estimates, particularly near transition boundaries.
If the same ayanamsa is subtracted from both solar and lunar longitudes, their difference remains unchanged. Therefore, the tithi is generally independent of the shared sidereal offset. This is different from nakshatra and sidereal zodiac calculations, where the selected ayanamsa can affect the resulting classification.
For tithi calculations, consistent longitude conventions and accurate timing matter more than selecting a particular sidereal zodiac. Do not combine coordinates from different instants or incompatible reference systems.
These examples use hypothetical celestial longitudes to demonstrate the exact angular classification rule.
| Sun Longitude | Moon Longitude | Elongation | Calculated Tithi |
|---|---|---|---|
| 100° | 106° | 6° | Shukla Pratipada |
| 100° | 127° | 27° | Shukla Tritiya |
| 100° | 190° | 90° | Shukla Ashtami |
| 100° | 274° | 174° | Shukla Purnima |
| 100° | 290° | 190° | Krishna Pratipada |
| 100° | 10° | 270° | Krishna Ashtami |
| 100° | 94° | 354° | Krishna Amavasya |
Suppose the Sun is positioned at 80 degrees and the Moon at 110 degrees. The angular difference is 30 degrees. Since the third tithi covers elongations from 24 degrees to just under 36 degrees, the result is Shukla Tritiya. The lunar day is approximately halfway through its angular interval.
Now suppose the Sun is at 250 degrees and the Moon is at 90 degrees. Direct subtraction gives −160 degrees. Adding 360 degrees produces an elongation of 200 degrees. The seventeenth tithi covers 192 to just under 204 degrees, so the result is Krishna Dwitiya.
Suppose the Sun is at 359 degrees and the Moon is at 2 degrees. The normalized elongation is 3 degrees, corresponding to Shukla Pratipada. Although the longitudes appear numerically far apart, they are separated by only three degrees across the zero-degree boundary.
This is why normalization is essential. A calculator that simply uses the absolute difference between longitudes would misclassify many lunar days near the beginning of the zodiac.
Compare the lunar calendar with related astronomical events and traditional chart calculations.
Understand the astronomical meaning of your result before applying traditional interpretations.
Shukla Paksha is the waxing half of the lunar cycle. It begins after the new-moon conjunction and progresses toward the full moon. Krishna Paksha begins after the full-moon opposition and continues toward the next new moon.
Traditional Hindu practices often associate the waxing fortnight with growth, expansion, and increasing lunar brightness. The waning fortnight is sometimes associated with reflection, withdrawal, and completion. These are traditional symbolic associations rather than measurable predictions of personal events.
Each paksha contains 15 tithis, but the amount of visible moonlight is not a simple linear function of tithi number. Illumination depends on the geometry of sunlight and the Moon's position relative to Earth.
A Panchang commonly identifies the tithi prevailing at local sunrise for the civil day's calendar designation. If one tithi ends shortly before sunrise and another begins, the new tithi may determine the day's listing.
Some observances use different rules, including whether a tithi prevails during a specified period. For example, a night-centered observance may require a different selection rule than a daytime ritual.
The Panchang Tithi Calculator identifies the lunar day at a chosen instant. It does not automatically decide which tithi governs a festival, fast, or ritual.
In some Vedic astrological traditions, the tithi at birth is considered alongside the birth nakshatra, planetary positions, and other chart factors. Birth tithi is determined by the exact moment of birth, so a date alone may be insufficient.
Use the actual birth time and historical UTC offset where available. For events near a tithi boundary, a more precise ephemeris is recommended.
Amanta lunar months end with Amavasya, while Purnimanta lunar months end with Purnima. These conventions affect the naming and grouping of lunar months but do not change the underlying angular definition of a tithi.
Regional Panchang traditions can also differ in festival observance rules. Always consult the relevant local calendar for authoritative religious scheduling.
These considerations help prevent common errors when comparing astronomical results with traditional calendars.
The lunar day is an angular interval, not a uniform period of clock time. Its duration changes with the relative apparent motions of the Sun and Moon. Two consecutive tithis can have noticeably different lengths.
At a given universal instant, geocentric lunar elongation is essentially the same worldwide. However, local sunrise and civil date depend on geographic location, so the traditional daily Panchang designation can differ between cities.
Approximate planetary formulas may produce transition times that differ from professional ephemerides. When the selected moment lies close to a tithi change, verify the result using authoritative astronomical data before relying on it for observances.
Each tithi spans 12 degrees of increasing elongation. The final value in each range is excluded, and the next interval begins at that boundary.
| Index | Paksha | Tithi Name | Elongation Range |
|---|---|---|---|
| 1 | Shukla | Pratipada | 0°–12° |
| 2 | Shukla | Dwitiya | 12°–24° |
| 3 | Shukla | Tritiya | 24°–36° |
| 4 | Shukla | Chaturthi | 36°–48° |
| 5 | Shukla | Panchami | 48°–60° |
| 6 | Shukla | Shashthi | 60°–72° |
| 7 | Shukla | Saptami | 72°–84° |
| 8 | Shukla | Ashtami | 84°–96° |
| 9 | Shukla | Navami | 96°–108° |
| 10 | Shukla | Dashami | 108°–120° |
| 11 | Shukla | Ekadashi | 120°–132° |
| 12 | Shukla | Dwadashi | 132°–144° |
| 13 | Shukla | Trayodashi | 144°–156° |
| 14 | Shukla | Chaturdashi | 156°–168° |
| 15 | Shukla | Purnima | 168°–180° |
| 16 | Krishna | Pratipada | 180°–192° |
| 17 | Krishna | Dwitiya | 192°–204° |
| 18 | Krishna | Tritiya | 204°–216° |
| 19 | Krishna | Chaturthi | 216°–228° |
| 20 | Krishna | Panchami | 228°–240° |
| 21 | Krishna | Shashthi | 240°–252° |
| 22 | Krishna | Saptami | 252°–264° |
| 23 | Krishna | Ashtami | 264°–276° |
| 24 | Krishna | Navami | 276°–288° |
| 25 | Krishna | Dashami | 288°–300° |
| 26 | Krishna | Ekadashi | 300°–312° |
| 27 | Krishna | Dwadashi | 312°–324° |
| 28 | Krishna | Trayodashi | 324°–336° |
| 29 | Krishna | Chaturdashi | 336°–348° |
| 30 | Krishna | Amavasya | 348°–360° |
Understanding the final tithis: Purnima is the fifteenth tithi and includes the approach to the exact full-moon opposition at 180 degrees. Amavasya is the thirtieth tithi and includes the approach to the next new-moon conjunction at 360 degrees, equivalent to zero degrees.
The exact astronomical full moon or new moon is a moment, not an entire tithi. The corresponding traditional tithi spans an angular interval leading up to that moment. This distinction is particularly important when comparing a tithi listing with an astronomical moon-phase calendar.
For further astronomical background, consult NASA's explanation of lunar phases and the United States Naval Observatory's lunar phase data. These resources describe astronomical lunar cycles but do not replace a regional Hindu Panchang.
Answers to common questions about lunar days, tithi timing, birth tithi, traditional calendars, and astronomical calculations.
A tithi is a lunar day defined by 12 degrees of increasing geocentric ecliptic elongation between the Moon and Sun. Thirty tithis form a complete lunar cycle, divided into two groups of 15 called Shukla Paksha and Krishna Paksha.
The calculator estimates the geocentric ecliptic longitudes of the Sun and Moon for the selected instant, subtracts the solar longitude from the lunar longitude, normalizes the result to 360 degrees, and identifies the corresponding 12-degree interval.
Yes, you can estimate your birth tithi by entering your birth date, local birth time, and historical UTC offset. If the exact time is unknown, the result may be uncertain because a tithi can change during the day.
Shukla Paksha is the waxing lunar fortnight, from new moon toward full moon. Krishna Paksha is the waning fortnight, from full moon toward the following new moon. Each consists of 15 tithis.
A tithi lasts until the Moon gains another 12 degrees of angular separation relative to the Sun. Its duration is variable, often around 19 to 26 hours, rather than exactly one civil day.
Not exactly. Tithi is a division of Sun–Moon elongation into 30 angular intervals. Moon phase describes the illuminated appearance of the Moon as viewed from Earth. They are related, but they are not interchangeable classifications.
The fifteenth tithi of Shukla Paksha is Purnima. It covers lunar elongations from 168 degrees to just under 180 degrees. At the exact 180-degree boundary, Krishna Pratipada begins under the astronomical interval definition.
The thirtieth tithi, Krishna Amavasya, covers elongations from 348 degrees to just under 360 degrees. At the exact conjunction, elongation returns to zero and Shukla Pratipada begins.
A traditional daily Panchang may assign the tithi prevailing at local sunrise, while this calculator evaluates the tithi at the specific clock time you enter. Differences may also result from ephemeris precision, time zone handling, or regional calendar conventions.
Yes. A tithi may end during a civil day and the next tithi may begin immediately afterward. Depending on the timing, more than one tithi can overlap the same midnight-to-midnight date.
A kshaya tithi is a tithi that does not prevail at sunrise on any civil day in a particular location. It still occurs astronomically, but its duration and timing place it entirely between consecutive local sunrises.
A vriddhi tithi is one that prevails at sunrise on two consecutive civil days. This happens when the tithi interval spans both sunrises. It does not mean the astronomical tithi has been duplicated.
No. Although it can estimate when Ekadashi occurs astronomically, religious fasting dates depend on additional sunrise and observance rules, sometimes including the treatment of Dashami and Dwadashi. Use a trusted regional Panchang for fasting decisions.
The geocentric tithi at a given instant does not require latitude and longitude. However, converting local clock time into a universal instant requires the correct UTC offset. Geographic coordinates are necessary for location-specific sunrise and traditional daily Panchang calculations, which this tool does not provide.
No. The displayed boundaries are estimates from a compact astronomical model. A high-precision ephemeris may give different results, especially near a boundary or for dates far from the model's best-supported era.
The result can provide preliminary lunar-day information, but a complete muhurta assessment may also require nakshatra, yoga, karana, weekday, sunrise, and other traditional considerations. This tool does not provide a comprehensive muhurta calculation.
Zero degrees is a valid ecliptic longitude. The calculator accepts values from 0 through 360 degrees, treating 360 degrees as equivalent to zero. It also handles differences that cross the zodiac's zero-degree boundary.
The calculator code processes the entered values within your browser and does not send them to a server. Other website services, such as analytics installed separately, may have their own data practices.
Use the Panchang Tithi Calculator to explore the astronomical relationship between the Sun and Moon, compare lunar fortnights, and learn how tithis form the foundation of the traditional Hindu calendar.