How to use it
- Enter the Date of birth and the Time on the clock where you were born. The time is needed for the rising sign.
- Type your birth city in Place and pick it from the list, or tick Enter coordinates instead.
- Click Calculate. The rising sign and the Sun and Moon signs appear at the top of the result.
- Read How the rising sign moves across the hour: if the sign changes within an hour, a small error in the time changes the answer.
What the rising sign is
The rising sign, or Ascendant, is the zodiac sign and degree that was crossing the eastern horizon at the moment of birth. It is the first house cusp of the birth chart. The Earth turns once a day, so the rising sign changes about every two hours, moving through all twelve signs in a day.
The Ascendant is calculated from the local sidereal time, the latitude and the true obliquity of the ecliptic, with the formula of Jean Meeus, Astronomical Algorithms (1998), chapter 14. The result is checked against the astronomy-engine horizon in the test suite of this site.
Why the time matters so much
Four minutes of time move the Ascendant by about one degree, and a sign lasts about two hours at the horizon. Near a sign boundary a few minutes of error can change the rising sign. The table shows the Ascendant 30 minutes before and after the time you gave, so you can see how close the boundary is.
The Sun and Moon signs do not depend on the hour: the Sun changes sign about once a month and the Moon about every two and a half days.
What this calculator does not include
- It does not give the houses or the other planets; use the birth chart calculator for those.
- It does not correct a birth time that was recorded in a different time zone or with a daylight saving error. Enter the local clock time that applied at the place on that date.
Worked example: New York, 4 July 1990, 14:30
At 14:30 daylight time in New York the Ascendant is 28°27′ Libra. The Sun is at 12°31′ Cancer and the Moon at 5°54′ Sagittarius.
The Ascendant crosses a sign boundary within the hour: at 14:00 it is at 22°33′ Libra, and at 15:00 at 4°21′ Scorpio. A birth time of 15:00 would give Scorpio as the rising sign, while 14:00 would still give Libra, which is why the time must be checked.
Frequently asked questions
What if I do not know my birth time?
Without a time the Ascendant cannot be found, because it depends on the hour. Use the birth chart calculator with the unknown-time option to see the planets and the Moon's range for the day.
How accurate is the rising sign?
The positions are accurate to about one arc minute, but the Ascendant is only as good as the birth time and the place. Each minute of time error shifts it by about a quarter of a degree.
Is my rising sign the same as my star sign?
No. Your star sign is the Sun's sign at your birth. The rising sign is the sign on the eastern horizon at that moment, so it is usually a different sign, and it changes through the day.
Why do sites give different rising signs for the same date?
They may use a different time zone, a different birth time, or a different place. Check the time zone and coordinates first; the chart on this page converts the time with the zone rules of that place and year.
Does this calculator store my birth details?
No. The date, time and place stay in your browser and are not stored or sent to us. Close the page and they are gone.
Sources
- astronomy-engine, the MIT-licensed library that calculates the Sun, Moon and sidereal time
- IANA Time Zone Database, the historical clock rules of each zone
- GeoNames, city coordinates and time zones (CC BY 4.0)
Figures and text last checked on Tuesday, November 10, 2026.