Your rising sign, or Ascendant, is the zodiac sign that was rising on the eastern horizon at the moment and place you were born. It needs your exact birth time and location, because it changes sign roughly every two hours. Someone born on 17 May 1990 at 14:30 in Amsterdam has a Virgo rising sign and a Taurus Sun.
What is a rising sign?
The rising sign is the point of the zodiac that was crossing the eastern horizon when you were born. Because the Earth turns once a day, all twelve signs rise in turn every 24 hours, each for about two hours. That is why two people born on the same day can have different rising signs and why astrologers insist on an exact birth time. In Western astrology the Ascendant is considered the “mask” or first impression you give, and is the starting point (first house) of the chart. Together with your Sun sign (core identity) and Moon sign (emotional nature) it is called the “big three”.
The result above lists all three, and the larger display focuses on the Ascendant.
How the calculation works
Your birth chart is a snapshot of the sky at the moment and place you were born. The tool converts your local birth time to universal time using the time-zone rules for the date (including daylight saving), calculates the Julian date and then uses published low-precision formulas: the Sun’s position from its mean longitude and equation of centre, and the Moon’s position from a series of the largest periodic terms. The Ascendant comes from the local sidereal time and your latitude. Signs are in the tropical zodiac, as used in Western astrology.
Accuracy and limits
- The Sun and Moon are accurate to about a third of a degree, enough for the sign unless you were born within the first or last degree of one.
- The Ascendant moves through all twelve signs every 24 hours, around one degree every four minutes. An error of 15 minutes in birth time can move it a few degrees, and sometimes into the next sign.
- Extreme latitudes (above about 66°) have no stable Ascendant calculation.
- Birth times on certificates may be rounded, so astrologers often “rectify” a chart against life events.
If you only know your approximate birth time, try the calculation for the start and end of the window. If the sign is the same, you are probably safe.
To explore a different part of the chart, see the moon sign calculator. For non-Western systems try the Chinese zodiac calculator, and for number-based systems the Numerology Calculator.
How to use this calculator
- Enter your date of birth and the local time from your birth certificate.
- Choose your place of birth, or type custom latitude, longitude and time zone.
- Read your rising sign, Sun sign and Moon sign.
- If your time is uncertain, test the earliest and latest possible times.
Key figures at a glance
| Changes sign | About every 2 hours |
|---|---|
| Needs | Exact birth time and place |
| Zodiac | Tropical |
| Precision | About 1° for the Ascendant |
Frequently asked questions
For the rising sign, yes: it changes about every two hours. For the Moon, the exact time matters less, except on days when it changes sign.
Choose the place of birth. The tool applies the historical time-zone and daylight-saving rules of that place.
Sun and Moon are accurate to a fraction of a degree. The Ascendant is accurate to about one degree if the time and place are correct.
The tropical zodiac, standard in Western astrology.
The positions are astronomy. The claims about personality are not supported by evidence.