Rising sign
Hidden card – fill in your birth data to reveal it
Rising sign calculator: what is my Ascendant?
Your rising sign, or Ascendant, is the zodiac sign that was rising on the eastern horizon at the moment and place of your birth. It changes on average about every two hours, so you need your birth time and birthplace to find it. It cannot be worked out from your Sun sign alone.
Hidden card – fill in your birth data to reveal it
- Updated
- How we calculate it
- Computed on your device
Enter your birth details to get your Ascendant sign and exact degree, plus a warning if it sits close to the edge of a sign. Your rising sign links to a short description of how it tends to show up in first impressions.
If you don't know your birth time, choose "time unknown": we list which rising signs were possible on your birth day and the clock-time window for each, so you can compare them with what you know about yourself.
How we calculate it
Planet positions come from Astronomy Engine, an open-source astronomy library (MIT license) whose author documents an accuracy of about ±1 arcminute. We use apparent geocentric positions on the true ecliptic of date (IAU 2006 precession and IAU 2000B nutation, with light-time and aberration) – the same definition most astrology software uses.
Your local birth time is converted to Universal Time with the historical rules of the IANA time zone database, including past daylight-saving changes and war-time clocks. City coordinates and time zones come from GeoNames. If a time was skipped or repeated because the clocks changed, we tell you instead of guessing silently. One honest limit: for births before about 1970 the database is not guaranteed to be complete, and a small town may have kept a different local time than the reference city of its zone. We always show the UTC offset we applied, so you can compare it with what you know (for example a time on a birth certificate).
We test the engine against NASA/JPL Horizons (DE441) for reference birth data: planets agree within 1 arcminute and the Moon within 2; the Ascendant and Midheaven, computed from Horizons sidereal time, agree within 3 arcminutes.
Everything runs in your browser. Your birth data is not sent to a server and nothing is stored.
Why the time matters so much
The Ascendant depends on local sidereal time – the Earth's rotation – and on your latitude. Outside the polar regions all 12 signs rise during one rotation of the Earth, but not for equal lengths of time (beyond the polar circles some degrees never rise at all, and the Ascendant can jump). At New York's latitude Aries and Pisces rise in about 1 hour 10 minutes each, while Leo, Virgo, Libra and Scorpio take about 2½ hours. In London the shortest signs take under an hour.
A difference of 10–20 minutes in birth time can therefore change your rising sign if you were born near a boundary. We show the degree and a cusp warning when it is within 1°.
Questions
How do they calculate the rising sign?
From your birth time converted to Universal Time, the local sidereal time at your birthplace and the tilt of the Earth's axis. Together they give the point of the zodiac crossing the eastern horizon – the Ascendant.
Can I find my rising sign without a birth time?
Not exactly. Without a time there are usually all 12 possibilities. Our calculator shows each possible rising sign with the time window when it applied on your birth day.
Can I know my rising sign from my Sun sign?
No. People with the same Sun sign can have any of the 12 rising signs – it depends on the hour of birth. A rough rule: if you were born around sunrise, your rising sign is often the same as your Sun sign.
What are my big 3 signs?
Your Sun, Moon and rising sign. You can see all three at once with the Big Three calculator.
Why do different websites give me different rising signs?
Usually because of the time zone. If a site applies the wrong historical offset or daylight-saving rule, the time is off by an hour – enough to change the rising sign. We use the IANA historical time zone rules and show the UTC offset we applied.
Sources
- Astronomy Engine (Don Cross) – source code and documentation, MIT license
- NASA/JPL Horizons System – reference ephemerides used to test our results
- IANA Time Zone Database (tz database) – historical time zone and daylight-saving rules
- IANA tz database – theory and accuracy of historical data
- GeoNames geographical database (CC BY 4.0) – city coordinates and time zones
- Astro-Databank – birth data with Rodden accuracy ratings
Astrology, numerology and the Chinese zodiac are offered for entertainment and self-reflection. They are not scientifically validated and are not a substitute for professional advice (medical, psychological, legal or financial). Astronomical positions are calculated precisely; interpretations are traditional symbolism, not predictions.