What the Zodiac Rising Sign Calculator does
This calculator works out your rising sign, or ascendant - the zodiac sign that was coming up over the eastern horizon at the moment you were born - from your birth date, exact local time and the latitude and longitude of the birthplace. It shows the ascendant degree, the midheaven, the local sidereal time behind the result, and how many minutes earlier or later the rising sign would have changed.
Unlike the Sun sign, the rising sign depends on the clock and the map. The Earth turns the whole zodiac past the horizon once a day, so a new sign rises roughly every two hours, faster for some signs than others and very unevenly at high latitudes. Pick a city from the offline list or type coordinates yourself; nothing is looked up online and your birth details stay in the browser.
How to use it
- Enter the birth date and the time as it was shown on local clocks, for example from a birth certificate.
- Choose the birthplace from the city list, or type its latitude and longitude (decimal degrees or degrees-minutes-seconds; south and west are negative). The nearest large city is usually close enough.
- Check the time zone. Choosing a city sets it for you; the zone's own rules for that date, including summer time, are applied automatically.
- Pick Western (tropical) for a Western horoscope or Vedic lagna (sidereal) for Indian astrology.
- Read the headline sign and degree, then the margin panel: it tells you the window of birth times that give this rising sign, so you know whether an uncertain time could change it.
Reading the results
The ascendant degree runs from 0 to 30 within the sign. Near 0 or 29 degrees you are close to the neighbouring sign, and the margin panel says exactly how many minutes away.
Local sidereal time is the star time at the birthplace: which part of the sky was due south at that moment. It is the quantity the ascendant is calculated from, shown so the working can be checked against a printed ephemeris.
The midheaven (MC) is the zodiac degree that was highest in the sky, due south in the northern hemisphere. It is not 90 degrees from the ascendant except near the equator, which is why house systems differ.
The table lists every rising sign for the whole local day. Signs of short ascension (Capricorn to Gemini in the northern hemisphere) rise in about an hour; signs of long ascension take up to three hours.
Worked example: sunrise in Mumbai
Born 15 August 1990 at 06:30 in Mumbai (19.076 N, 72.878 E). India Standard Time is UTC+05:30, so the moment is 01:00 UTC.
Greenwich apparent sidereal time at that instant is about 22h 33m; adding the east longitude (72.878 / 15 = 4h 51.5m) gives a local sidereal time of 3h 24m 15s, or 51.06 degrees.
With the true obliquity of 23.44 degrees and a latitude of 19.076 degrees, the ascendant formula gives an ecliptic longitude of 143.56 degrees: 23 deg 33' Leo. The Sun was at 21 deg 57' Leo, which is what you would expect a quarter of an hour after sunrise.
Leo was rising from 04:45 to 06:57 local time, so a birth up to 27 minutes later would still be Leo rising; at 06:57 or later it becomes Virgo.
Formulas and scoring rules
- Local sidereal time
LST = GMST + nutation x cos(obliquity) + east longitudeGMST = 280.46061837 + 360.98564736629 x (JD - 2451545.0) + 0.000387933 T^2 - T^3 / 38,710,000 degrees (Meeus 12.4), with JD on Universal Time.- Ascendant
ASC = atan2(cos LST, -(sin LST x cos e + tan latitude x sin e))e is the true obliquity of the ecliptic (about 23.44 degrees). atan2 puts the result in the eastern half of the sky.- Midheaven
MC = atan2(sin LST, cos LST x cos e)- Sidereal (lagna)
lagna = ASC - Lahiri ayanamsaAbout 24.2 degrees in 2026.- Birth-time margin
earliest and latest times with the same sign, found in 2-minute steps then by bisection to the second
Limitations: what the result does not prove
- The answer is only as good as the birth time. A time rounded to the nearest quarter of an hour can change the rising sign when the margin shown is small.
- City coordinates are city centres. For most places the difference across a city moves the ascendant by a small fraction of a degree, but for a birth close to a sign change, use the exact coordinates.
- Inside the Arctic and Antarctic circles part of the zodiac never rises, so the ascendant is undefined there and the tool says so instead of giving a number.
- What a rising sign is said to mean is astrological tradition, not science, and is labelled that way.
Privacy: where your data goes
Everything you paste, type or drop is processed in this browser tab. It is not uploaded, logged, stored or sent to analytics. Session recording and tag-manager scripts are switched off on this page.
Standards and sources
- NASA JPL Horizons - solar system ephemeris used to check positions - checked 19 Sep 2026
- Paul Schlyter - How to compute planetary positions (sidereal time and ascendant)
- IANA Time Zone Database
Frequently asked questions
What is my rising sign if I know my birth time?
Enter the date, the time and the birthplace, and the tool computes which sign was on the eastern horizon at that minute. You get the sign and degree, plus the window of times that would give the same answer.
Can I find my rising sign without a birth time?
Not reliably. All twelve signs rise during a single day, so without a time any of them is possible. The day table shows each sign's window, which can help if you know roughly whether you were born in the morning, afternoon or night.
Is the ascendant the same as the lagna?
Both mean the rising degree of the zodiac. The Western ascendant is measured in the tropical zodiac; the Vedic lagna is the same point measured in the sidereal zodiac, so it is usually about 24 degrees earlier and often one sign earlier.
Why does the rising sign change every two hours?
The Earth spins once a day, carrying the twelve signs past the eastern horizon, which averages two hours a sign. The ecliptic is tilted, so some signs rise at a steep angle and pass quickly, while others rise slowly; at mid-northern latitudes the range is roughly one to three hours.
Does the birthplace really matter for the ascendant?
Yes. Longitude shifts local time against the stars by four minutes per degree, and latitude changes the angle at which the zodiac meets the horizon. The same clock time in Delhi and in London gives different rising signs.
How accurate is this rising sign calculator?
The sidereal time follows Meeus and the obliquity includes nutation, so the ascendant is accurate to a small fraction of a degree for a given time and place. In practice the birth time, often rounded, is the only real source of error.
Last reviewed by the A2Z.Tools team against the sources listed above.
